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Old 05-07-2018, 02:26 PM   #1
cruizin01
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A/C line, condener, dryer components and fitment issues

Working on adding the necessary pieces for the a/c on my '78 build. The cab was an a/c cab so all that is there and correct. (the cab was an 87 and the a/c components were early mid 80's that was used on the cab) I'm running into issues with the dryer, lines and condenser. Ill try to give accurate info and if anyone has any tips or help or even parts I would appreciate it.

I got a new spectra condenser but I don't have anything to mount it with. There are large holes on rad support and it appears the condenser needs spaced out to clear everything on the core support. Anyone know what hardware is used?



I'm also missing some sort of a/c junction to connect the condenser fittings to the lines on the other side of the rad support. I see something gray'd out in the LMC catalog but can't find any pics, or info of the necessary piece needed.




My next issue is the hose that comes across to the dryer. The replacement hose requires a "J" shaped line that connects into the bottom of the dryer. It doesn't fit quite right and forces the J into the evap housing.



The dryer also doesn't fit right when connected to the evaporator. Its smudged up against the relay mounted to the evap. The dryer bracket I got also doesn't match up to the bracket that's attached to the evap housing.




And... The sensor I got doesn't thread onto the dryer. I'm not sure if its correct or not. The connector is correct for the plug I have. What specifically should this sensor be for? I also have a fitting on the hose that connects at the bottom of the evaporator and I have no idea what connects to it.



Thanks for any help anyone can provide.
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Old 05-07-2018, 03:17 PM   #2
ultrahd4me
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Re: A/C line, condener, dryer components and fitment issues

I'm fairly certain the earlier 80's A/C setup is a lot different than the late. You will need the later style drier without the tube on the bottom and the matching line set. I would recommend the APDI/Pro 7013642 condenser because its a perfect bolt in and also a parallel flow for 134. As you have found out, the spectra does not fit. If you are replacing the compressor and don't have it, there is a difference in coil position (9:00 or 12:00) and that also effects the compressor clutch and pulley. I hope this helps.
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Old 05-07-2018, 04:21 PM   #3
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Re: A/C line, condener, dryer components and fitment issues

Quote:
Originally Posted by ultrahd4me View Post
I'm fairly certain the earlier 80's A/C setup is a lot different than the late. You will need the later style drier without the tube on the bottom and the matching line set. I would recommend the APDI/Pro 7013642 condenser because its a perfect bolt in and also a parallel flow for 134. As you have found out, the spectra does not fit. If you are replacing the compressor and don't have it, there is a difference in coil position (9:00 or 12:00) and that also effects the compressor clutch and pulley. I hope this helps.
Do you know if all rad supports will support the condenser that exits out the passenger side? I assume pre 80 rad supports dont support this but Im not sure. I do already have the big compressor for the big block. Its new and I assume the hoses for the pancake style compressors would not work.

I see what you're saying with the dryer. Im just concerned I wont be able to make a later drier work if I have to use the hoses from an earlier style because of the condenser.. ugh.
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Old 05-07-2018, 04:34 PM   #4
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Re: A/C line, condener, dryer components and fitment issues

I just don't know for sure on the core support. I've rebuilt the A/C on almost all my trucks but they have been 83-87. You may have to make custom lines for your setup.
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Old 05-07-2018, 10:50 PM   #5
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Re: A/C line, condener, dryer components and fitment issues

Randomly found these tonight on eBay. They should be the 2 lines I need to run from the condenser through the core support. At least by their description. I wish I could test fit them...haha.
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Old 05-12-2018, 05:07 PM   #6
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Re: A/C line, condener, dryer components and fitment issues

Update.

I went ahead and purchased the lines above.

They are just what I needed. My rad support has the hole for the grommet and it positions the lines correctly as well. I need to mount my condenser before installing them.

On that note I found some hardware from classicparts.com that appear to be what Im after to mount the condenser.



They should fit through the large hole in the rad support and then a bolt is used to hold the condenser in place. Maybe I could find these locally but Im just gonna order them along with the bolts.

I was also able to get the dryer to fit by bending the evap line a bit. It was a little softer than I was expecting so that gets me the room I need.




I need to come up with a bracket yet. Ill may try and make something that holds the line in place versus using the big round dryer bracket. We'll see.

I still need to order a new switch. I believe the one I need for the dryer is a high pressure switch, correct?

But that still leaves me with an opening on the liquid line to the evaporator. It doesn't appear to be used on later trucks thus I have no connector on my harness. I think it can be wired in series but Im not sure what switch I need. I found a couple that claim to be low pressure. All the pictures I can find make it seem like the bottom picture is used for the dryer but should that be on the high side? maybe it doesn't matter?

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Old 05-12-2018, 11:06 PM   #7
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Re: A/C line, condener, dryer components and fitment issues

That switch goes on your accumulator, on the back port pointing towards the blower motor. There should be a connection to it coming off the top of your evaporator housing.
See the pics ultra posted above.

Your liquid lines just have hi-side charging ports. This is used for your manifold gauges. Only charge into the accumulator (low side).
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Old 05-13-2018, 10:35 AM   #8
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Re: A/C line, condener, dryer components and fitment issues

I understand there is a switch there. Im just not sure which one gets used. I think its the bottom one in my pictures. I have the green and dark green connector for it.

Also on 70's trucks there is a sensor that goes in the lower liquid line. As seen in the picture below. This is the one Im not certain on as well as not having any connector to plug into it.
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Old 05-13-2018, 11:57 AM   #9
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Re: A/C line, condener, dryer components and fitment issues

Any hardware store with Hillman fasteners should have the rubber well nuts.

The stock R12 setups on the 73-87 trucks only have a low pressure cutoff switch LPCO on the accumulator. It should be the fitting pointing toward the blower fan. The other fitting should have a Schraeder valve and threads for R12 low side manifold gauges.

A high pressure cutoff switch HPCO, if someone added the fitting for it, should be on the compressor head or on the High Pressure hose fitting off the compressor.

A fitting further away from the compressor should be the Schraeder valve and fitting for the high side hose on your R12 manifold gauge set.

The LPCO and HPCO are wired in series between the AC control head in the dash and the compressor clutch.
If possible I usually get a Sanden compressor with the HPCO bung in the head or hoses for the Harrison A6 or A4 compressors with the HPCO bung installed.

I usually install a Snubber diode across the compressor clutch coil if it's not already present in the compressor plug... Even if you don't add a HPCO switch I would make sure a snubber diode is installed properly. It keeps high voltage spikes generated, when the electromagnet coil switches off, from backfeeding into the electrical system of the truck.

The easiest way to add one is the GM ATM fuse package AC diode... Littelfuse 02400104P 1A Mini Diode GM #12135037 and a Metripack 280 sealed ATM fuse holder.
You can buy the diodes and Metripack ATM fuse holders on Amazon.

Fuse holders can be purchased already terminated with wire pigtails for soldering into your wires or in kits with terminals, seals, housings, and cover and U provide the wire.

Attach one wire to the clutch power and one to the ground. Insert the diode with the Cathode arrow and stripe pointing toward the clutch power and the anode end (wide back of the arrow) to ground. This blocks current from flowing through the diode to ground but allows the high voltage AC inductive spike generated by cutting clutch electromagnet coil power to flow back into the clutch coil and quickly, and harmlessly, dissipate rather than backfeeding into the vehicle power system.

This video is a visual in-depth Electronics tech explanation on Snubber diodes and why to use them around Induction coils like relays and electromagnets. He shows scope traces of the inductive spikes and the way snubber diodes impact the voltage levels of the spikes using a test circuit on a breadboard. His relay is a much smaller electromagnet than the AC compressor clutch. I've seen over 500V spikes from AC clutches...
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1969 Dodge Polara 500 B383, A833
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1976 Chevy K20, 6.5L, NV4500/NP208
1986 M1008 CUCV
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
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Last edited by hatzie; 05-13-2018 at 12:08 PM.
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Old 05-13-2018, 06:29 PM   #10
cruizin01
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Re: A/C line, condener, dryer components and fitment issues

Thanks Hatzie for all the info.

Ill go ahead and order parts for the diode mod.

As I mentioned in my PM though, I definitely have an additional port on my liquid line that needs something... I assume if I find the right switch I can just use it to plug the hole. And just use the LP switch on the dryer.



I was able to get the rubber nuts I need to mount the condenser at lowes today. Unfortunately the condenser didn't mound up close enough for the crossover pipes. So I had to make a couple new small brackets to mount the condenser closer to the drivers side. Everything fit then.

My next issue was getting the stiff liquid line to fit with the crossover pipe. It was 2-3" short when trying to get it to mount. So I ended up straightening the liquid line out and rebending it. Its not overly pretty but it works. Everything else fits up. So now I just need a couple orings, a couple switches and a bracket to hold the dryer in place.


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Old 05-14-2018, 01:35 PM   #11
hatzie
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Re: A/C line, condener, dryer components and fitment issues

The proper location for a standard LPCO Switch is on the dryer.

The pictures help. I'm a pretty visual person...

The hose from the condenser to the orifice tube in the base of the evaporator is on the high pressure side of the system. That port could be used for a HPCO switch. I usually install them close to the compressor but that location is sufficient for the task and easier to wire. I would add one if you intend to use R134a.

The switch should be wired in series between the LPCO and the compressor clutch.

LPCO is a Normally Open switch that usually closes at @ 25-30PSI.
HPCO is a Normally closed switch that usually opens at @385-425 PSI.

Here's a quick N dirty sketch of the clutch wire with a LPCO & HPCO switch and Snubber diode installed.

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1959 M35A2 LDT465-1D
1967 Dodge W200 B383, NP420/NP201
1969 Dodge Polara 500 B383, A833
1972 Ford F250 FE390, NP435/NP205
1976 Chevy K20, 6.5L, NV4500/NP208
1986 M1008 CUCV
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.

Last edited by hatzie; 05-14-2018 at 01:42 PM.
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Old 05-14-2018, 01:56 PM   #12
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Re: A/C line, condener, dryer components and fitment issues

Yeah-I went thru this problem too only I added a GM style serpentine swap to a 77. Because the AC required using 88-up style pick-up hoses, I opted to NOT use the OE style drier. I did however re-use those 2 small prebent lines you seen on that Ebay auction-those are correct. I too have those jam nuts but the upper holes are not the same diameter as the lower ones. I used a uni-bit to make them match. I used a Spectre condensor and had to adjust the soldered-on tube to line up to the AC adapter lines on the drivers side. The only line that is a problem to source now is the liquid crossover line over the top of the radiator support but I had a local hydraulic shop make that one for me. The drier clamp I too had to modify-I think I just used an 88-up style clamp.
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Old 05-14-2018, 03:03 PM   #13
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Re: A/C line, condener, dryer components and fitment issues

Quote:
Originally Posted by gmachinz View Post
Yeah-I went thru this problem too only I added a GM style serpentine swap to a 77. Because the AC required using 88-up style pick-up hoses, I opted to NOT use the OE style drier. I did however re-use those 2 small prebent lines you seen on that Ebay auction-those are correct. I too have those jam nuts but the upper holes are not the same diameter as the lower ones. I used a uni-bit to make them match. I used a Spectre condensor and had to adjust the soldered-on tube to line up to the AC adapter lines on the drivers side. The only line that is a problem to source now is the liquid crossover line over the top of the radiator support but I had a local hydraulic shop make that one for me. The drier clamp I too had to modify-I think I just used an 88-up style clamp.
Thanks Gmachinz for the input. I was able to make everything work but yes I had all those same issues. I modified the liquid line enough to fit. Ill search out another dryer clamp. Thanks.
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Old 05-14-2018, 03:04 PM   #14
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Re: A/C line, condener, dryer components and fitment issues

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The proper location for a standard LPCO Switch is on the dryer.

The pictures help. I'm a pretty visual person...

The hose from the condenser to the orifice tube in the base of the evaporator is on the high pressure side of the system. That port could be used for a HPCO switch. I usually install them close to the compressor but that location is sufficient for the task and easier to wire. I would add one if you intend to use R134a.

The switch should be wired in series between the LPCO and the compressor clutch.

LPCO is a Normally Open switch that usually closes at @ 25-30PSI.
HPCO is a Normally closed switch that usually opens at @385-425 PSI.

Here's a quick N dirty sketch of the clutch wire with a LPCO & HPCO switch and Snubber diode installed.
Hatzie, Thanks again for all your work. Id like to add the correct switch for future proofing even if I do R12 right now. Any idea on how to find the correct HPCO switch for my line? I ordered a couple LPCO switches in hopes of them at least plugging the hole but would like to have the right switch to wire in.
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Old 05-14-2018, 09:32 PM   #15
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Re: A/C line, condener, dryer components and fitment issues

My compressor leaks. Do I need to replace anything else? Or just the compressor itself?
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Old 05-15-2018, 05:35 PM   #16
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Re: A/C line, condener, dryer components and fitment issues

After some research it appears some companys make binary switches. So if I can find the correct thread style for the opening on the liquid line I can use one of the aftermarket hi/lo switches. Either as the only switch or in conjunction with the low switch on the dryer.
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Old 05-17-2018, 12:37 AM   #17
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Re: A/C line, condener, dryer components and fitment issues

I don't like the binary switches.
A 1996 and later R134a HPCO switch is what you want. Ask the outfit that sold you the hoses what the threads are... or measure them.
The stock 1984 LPCO shouldn't be a problem for R12 & R134a as long as you aren't going to run some exotic refrigerant like hydrocarbon blends that have very low liquid and vapor side pressures.
You don't really need a HPCO for R12... R134a has higher liquid pressures.
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1959 M35A2 LDT465-1D
1967 Dodge W200 B383, NP420/NP201
1969 Dodge Polara 500 B383, A833
1972 Ford F250 FE390, NP435/NP205
1976 Chevy K20, 6.5L, NV4500/NP208
1986 M1008 CUCV
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.

Last edited by hatzie; 05-17-2018 at 12:44 AM.
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Old 05-17-2018, 08:01 AM   #18
cruizin01
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Re: A/C line, condener, dryer components and fitment issues

Quote:
Originally Posted by hatzie View Post
I don't like the binary switches.
A 1996 and later R134a HPCO switch is what you want. Ask the outfit that sold you the hoses what the threads are... or measure them.
The stock 1984 LPCO shouldn't be a problem for R12 & R134a as long as you aren't going to run some exotic refrigerant like hydrocarbon blends that have very low liquid and vapor side pressures.
You don't really need a HPCO for R12... R134a has higher liquid pressures.
Ill keep that in mind on the switches. Thank you.

I ordered a couple switches and received them yesterday.

The first one is a GPD 1711250 that threads into the accumulator and appears correct and looks similar to other ones Ive seen. Though the description on a few sites describes it as a clutch cycle switch. I found a Four Seasons 35751 after the fact and it looks the same but is described as a R12 pressure switch.

I also ordered a Four Seasons 35757 which threads onto the liquid line and appears mostly correct. My concern is it did not come with an oring. I found one that fits correct but the switch still bottoms out on the liquid line base without me having to use a wrench. I'm concerned the oring may not have gotten any "squish" and will/would leak.
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Old 05-17-2018, 08:42 AM   #19
hatzie
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Re: A/C line, condener, dryer components and fitment issues

I've seen LPCO switches called clutch cycling switches. Different name same part.
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1959 M35A2 LDT465-1D
1967 Dodge W200 B383, NP420/NP201
1969 Dodge Polara 500 B383, A833
1972 Ford F250 FE390, NP435/NP205
1976 Chevy K20, 6.5L, NV4500/NP208
1986 M1008 CUCV
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8


RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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