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Old 08-09-2018, 02:41 AM   #26
Cabnchassis
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Every GMT400 I've owned, after they went to the center mounted heater, has had electrical issues at the switch panel. The high speed heater switch has been melted at the harness connector, in almost every single one I've ever pulled out. I've pulled 20-25 at wrecking yards, all but 2 showed damage, neither worked in the 3rd or 4th position lol.

Traded a 95 k1500 burb for a 98 Grand Prix GTP, blew the trans then traded it for a 91 k2500 burb with a 6" lift....which is now a 91 Honda CR500 but I digress....The heater panel actually started smoking on the highway, ruined the controls, would have caught fire without attention. Most of them aren't a fire hazard, just don't work on the higher speeds, but it's startling how many of these trucks have visible damage around the high speed switch.

Not sure if its related to the switch based on what you've done, but one time I pulled a heater fuse in summer to fix the control panel in my 91 R3500. Took two weeks to figure out why the transmission was stuck in limp mode. Someone at GM didn't see any problem with powering the DRAC or whatever that thing is off a fuse that you might pull for a hundred reasons, and still need to drive down the road.
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Old 08-09-2018, 05:52 AM   #27
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Good to hear you are back to the original issue.

If you haven't checked it already, check the orifice tube. If it's clogged, then you might experience the issue you have now. IIRC on these trucks it is up near the radiator on the passenger side, just inside the grill.
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Old 08-09-2018, 09:10 AM   #28
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

But I don't have frost on the vents or dryer so I never considered the issue to be the O tube.

That would cause the low side to have some much pressure?

Just seems like I would have other issues right? tell-tell signs.

In the end I guess I gotta take it to someone. Hate doing it, but i think I've gone as far as I can.

I really appreciate all the help seriously.

I just wish there was a way to know for sure but it feels like the condenser is involved somewhere.
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Old 08-09-2018, 09:35 AM   #29
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

If the orifice tube is open too much, you are putting too much freon through the system and will get the freeze up. If it's closed too much or clogged, you could see high pressure on the low side as the pressure can't be relieved due to the clog.

But yeah, it might be time to take it somewhere just to get it resolved, especially in that heat.
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Old 08-09-2018, 10:21 AM   #30
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

If I open it up and see that it is clogged. What is that a tell-tell sign of? If it's metal, I am assuming that is my brand new compressor gone bad.

Just learning here.
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Old 08-09-2018, 01:04 PM   #31
sntrym95
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Could be pieces from the old compressor, since you had it replaced.
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Old 08-09-2018, 03:02 PM   #32
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

The orifice tube is located at the junction in the A/C line on the passenger side inner fender. It is directly below the air cleaner.

The junction has aluminum threads on one side, and steel on the other. Sometimes threads get damaged and then youll have to buy new lines. The orifice tube can really be stuck in there too. A small needle nose pliers will work, but sometimes they are so stuck they break. Note the orientation upon removal. You don't want to install the new one backwards.

Was the new compressor installed by a shop? Most shops require replacing the dryer, the orifice tube, and flush the lines to get the warranty on the compressor.

Do you have rear a/c, and did it previously work too?
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Old 08-10-2018, 10:39 AM   #33
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

No the rear AC is not blowing cold either. Same as front. But it did work like front until AC compressor stopped engaging last Saturday.

Yes I replaced the compressor, dryer and o tube when I installed new compressor. I vac'd it down and did refill.

When I hook up test light to battery positive and touch compressor wire harness from back of compressor - the AC clutch will engage and I get cold air.

AC Relay is brand new. All fuses good.

Can a bad condenser cause this? I only ask this question because I go back to my original problem that was it not blowing cold at stop lights - idle.
Can the condenser completely fail and cause compressor not to engage?

I can't shoot dye into system to look for leak because AC won't engage.

Should I VAC it all the way down, and start from scratch? I guess I could take everything apart and look at the o tube.

Just not sure what the smartest approach would be money wise.

I do know the condenser has got some miles on it for sure. I would go ahead and replace the condenser if I knew a failed unit could cause the AC compressor to not come on.

Last edited by shultzee13; 08-10-2018 at 10:41 AM. Reason: Missed a question
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Old 08-11-2018, 10:56 AM   #34
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Low pressure side 95 psi (2:30 o'clock)
High pressure side 100 psi (8:30 o clock)

Reading on gauges
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Old 08-11-2018, 11:58 AM   #35
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

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Low pressure side 95 psi (2:30 o'clock)
High pressure side 100 psi (8:30 o clock)

Reading on gauges

is that compressor running or compressor not running those look like normal static pressures when compressor is not engaged
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Old 08-11-2018, 12:00 PM   #36
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

have you checked the low pressure switch at the a/c drier these go bad alot and ive replaced alot it is a 2 wire switch i normally jump with a paper clip if i jump and compressor comes on pressure switch is bad it just screws off and has a valve that willc lose when screwed off so u dont lose and feron
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Old 08-11-2018, 01:01 PM   #37
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When jumped compressor still donít come on.
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Old 08-13-2018, 12:02 PM   #38
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Increased pressure readings is usually due to a blocked orifice tube. when you replaced the compressor 6 months or so ago, did you check the orifice tube?
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Old 08-13-2018, 01:28 PM   #39
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

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Increased pressure readings is usually due to a blocked orifice tube. when you replaced the compressor 6 months or so ago, did you check the orifice tube?
read post #33
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Old 08-13-2018, 02:47 PM   #40
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O tube replaced then. Brand new one now as well.
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Old 08-13-2018, 03:11 PM   #41
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Brand new compressor, o tube and condenser. Compressor cycles on and off every 5 or six seconds. Freon levels are good. Low and high pressure switches have all been changed.
At least new compressor comes on.
Crazy
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Old 08-13-2018, 04:03 PM   #42
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Maybe in the end, I overfilled it on the new setup. I vac'd it all down to 0 and I know for sure Suburban takes about 5 cans of the small cans because of the rear air.

Funny thing is it cycled correctly after just the 2nd can. That's just weird to me.

I will finally wave the white flag of surrender.

I appreciate each of you guys putting up with me and my starkiness.
Frustrating when something seems so simple.
I didn't mean to be short with anyone.

Thanks again and God bless to each of you.
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Old 08-13-2018, 10:55 PM   #43
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Glad to hear it's running correctly now, and you can stay cool in the Texas heat.
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Old 08-14-2018, 06:35 AM   #44
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

That is good, full charge on a 98 suburban with rear air is 4 pounds. How much are in your small cans?
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Old 08-14-2018, 09:10 AM   #45
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

Quote:
Originally Posted by shultzee13 View Post
Compressor cycles on and off every 5 or six seconds.
Is this still occurring?
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Old 08-15-2018, 04:53 PM   #46
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Is this still occurring?
Yeah still happening. Low side is high. High side is low. Compressor still cycling. Crazy.
Could the rear expansion valve being stopped us cause this?
Another guy suggested that.
Itís the small cans and i put 6 cans in it and stopped. I didnít want to blow something up.
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Old 08-15-2018, 05:05 PM   #47
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Re: 98 Suburban 2WD/5.7L AC Issue - HELP

6 12 ounce cans and i stopped. Iím right at the 4 pound mark. Still have constant recycling and low side high high side low pressures. Is there a way to eliminate the drier ?
I donít have frost on the vents.
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