Finally getting AC

[mister.freeze]

So after owning my 72 K5 for 22 years, I'm finally getting around to putting air conditioning back in it. I installed the major components and am looking for a place locally to have the hoses crimped.

After installing the Condenser, the truck ran really hot. I did a drain and flush, and checked the thermostat. All good. It's a universal AC kit, so the condenser has it's own fan. I tied it into the electric radiator fans, and the helped a little. All this BEFORE even servicing and running the AC system. I have 2 12" fans on the radiator that before the condenser install kept the temp needle in the first 1/4 of the gauge. The condenser can't be blocking that much air, can it? When I run the system and the condenser gets warm, things will just get worse, probably. Thoughts? any chance of a coincidental water pump or temp sensor issue? Thanks all.

[hemi43]

Originally Posted by mister.freeze

So after owning my 72 K5 for 22 years, I'm finally getting around to putting air conditioning back in it. I installed the major components and am looking for a place locally to have the hoses crimped.

After installing the Condenser, the truck ran really hot. I did a drain and flush, and checked the thermostat. All good. It's a universal AC kit, so the condenser has it's own fan. I tied it into the electric radiator fans, and the helped a little. All this BEFORE even servicing and running the AC system. I have 2 12" fans on the radiator that before the condenser install kept the temp needle in the first 1/4 of the gauge. The condenser can't be blocking that much air, can it? When I run the system and the condenser gets warm, things will just get worse, probably. Thoughts? any chance of a coincidental water pump or temp sensor issue? Thanks all.

Are you using a shroud that covers the whole rad surface? Are you using an aluminum rad? Just placing a couple fans over the rad will not be sufficient especially if they are not located right against the cooling fins. Any gap will allow the air to just recirculate around the fans, and having any extra obstructions like your AC condenser will just increase the problem because the air will take the path of least resistance.
Pics?

[mister.freeze]

No, I do not have any kind of shroud. However, the 2 fans as they are have done the job for 20 years. But I was thinking that I may just have to fab a shroud to make the whole setup more efficient. Is that really the answer to my problem? The radiator is not aluminum.

[YellowK5]

Silly question but ..Do you know if the fans are all pushing or pulling the air the correct direction?....And as posted above you need a good shroud

[hemi43]

Originally Posted by mister.freeze

No, I do not have any kind of shroud. However, the 2 fans as they are have done the job for 20 years. But I was thinking that I may just have to fab a shroud to make the whole setup more efficient. Is that really the answer to my problem? The radiator is not aluminum.

Is it the solution? I think so.
If it was me, I would buy or build an aluminum rad, and get a new dual electric fan from a reputable company like Flex-A-Lite with a built-in shroud. You can buy these in different sizes to fit your rad. I don't think its worth your while to try and fab a shroud for your existing fans.
I've built quite a few aluminum rads over the years, and have never had any problems with overheating with the rad itself. It was always poor air circulation that caused issues.
Thankfully these trucks can take a large rad, unlike some street rods that can be a pain to keep cool.
Another thing to consider is how you are turning the fans on and off. Don't use the sensor bulb that comes with the fans. They are easy to install, but never work properly. Best way is to use a temp sensor mounted directly in the water jacket.
Hope this helps.

[mister.freeze]

Like I said, for 20 years, the 2 fans as they are have been more than adequate. They are pulling air (the one on the condenser is a pusher) and are run via a relay off a switch on the ignition circuit. Here in Houston, I let the thermostat do the hard work of regulating temp as opposed to a temp sensor turning them on and off: they just stay on. It just surprises me how much of a difference simply mounting the condenser has made. If I had the budget, I'd just get an an Aluminium CoolIt radiator and fan setup for this truck. For now, though, I have to go with what I got. My skill and tooling is enough to fab a decent shroud (at least better than what I have) so I'm not afraid to go that route.

[hemi43]

I just noticed something. Your condenser is not tight against the surface of the rad and at an angle. That large air gap between them can cause lots of turbulence and prevent a smooth airflow through the rad. Might be worth looking at. Using a pusher fan as well as the two puller fans is something you should avoid also, and wont be needed with a proper shroud.

[mister.freeze]

The mfg instructions said the condenser shouldn't be more than 2" from the radiator... I could re-bracket it and have it touching the radiator. Maybe I'll do that first (easier than a shroud at this point). NOT discounting the need for a shroud, I've just been doing so well for so long without one.

[Richard]

An easy way to check if overheating has anything to do with the condenser is to remove it and run the truck. You do not have any hoses connected so should be fairly easy. As for a shroud I would not recommend a flat plate on or 1/2" from the radiator. IMO they do more harm than good. Same or better results is had from your existing setup with fans against radiator.

[mister.freeze]

I'll try removing the condenser. Then I'll mount it closer to the radiator. Might be a few weeks tho

[mister.freeze]

Ok, so now the condenser is right up against the radiator. Will test this weekend on the freeway.

[mister.freeze]

so moving the condenser against the radiator did not help. Sooo... I'll be making a shroud. Should I now remove the condenser fan?

[Richard]

Did the overheating problem go away with the condenser completely removed?

[mister.freeze]

I'll be checking that today or tomorrow; removed the condenser last night. My guess is yes, as everything will be back the way it's been for the past 20 years.

[Richard]

Interested in seeing the results of removing it. I agree with a statement in the first post of this thread " The condenser can't be blocking that much air, can it?" Even if the cooling goes back to normal (Do not think it will) I would think the cooling system is marginal if it overheats even without the A/C on.

[mister.freeze]

so I removed the condenser and took a drive down the freeway. As I thought, back to like it's been for the past 20 years. So today or tomorrow I will build a shroud. I'm inclined to remove the condenser fan, but I'd like feedback on this.

[YellowK5]

With dual electric fans I would think you wont need the condenser fan at all..

[Richard]

Originally Posted by mister.freeze

so I removed the condenser and took a drive down the freeway. As I thought, back to like it's been for the past 20 years. So today or tomorrow I will build a shroud. I'm inclined to remove the condenser fan, but I'd like feedback on this.

Interesting finding. What would concern me is I had always believed traveling down the highway at speed is typically best case scenario as far as air flow is. At speed the condenser fan does not typically run if a pressure switch is installed and radiator fans are not running/fan clutch disengaged. A fan shroud is used to focus air flow though the rad from the fans. That said- a shroud will not improve air flow through rad at highway speeds in a properly operating cooling system.

[mister.freeze]

so I installed everything and while better, it's still not great. For the past 20 years I've run my 2 electric fans as pictured and temp only ever got up to the first hash mark on the gauge. Sometimes, in traffic, in the summer, it would get pretty hot, but that always ended up being low coolant or one of the fans quitting (bad electrical connection). Now, with everything installed, the needle is straight up on the highway. This is without the help of the condenser fan. While this is in the acceptable operating temp (right?), I'm worried about running the AC in summer traffic. The system is set up to run the condenser fan while the compressor runs; should I leave it that way or remove the condenser fan?

The fans are right at 2" from the radiator. The shroud was cheap and easy enough to build that I'd be willing to do it again should that gap need to change. Should it?

[mister.freeze]

This is where my temp always has been before messing with the condenser.
I removed the condenser to take the fan off of it and ran around with the new shroud. Not as cool as it used to be! Cooler than with the condenser and no shroud, though. So I took off the shroud and am back to square one with just the fans on the radiator. As stated previously, max flow should be at highway speeds, and it is. In the past, I could turn off the fans at highway speeds and stay cool. If I forgot to turn them back on and got hot at at a stop or in traffic, turning them on would bring me back down to the pictured temp. Soooo... I'm going to try mounting the condenser up against the radiator with no condenser fan and no shroud. I think the shroud was hindering my highway flow, but improving my low-speed flow. If this doesn't work, I'll try mounting the condenser FARTHER from the radiator and using it's supplied fan to isolate it from the radiator. Thoughts?

[YellowK5]

Do you have a thermostat in the truck? I suspect/Wonder is that is a bit low on the gauge..Does any one here on the boards know what the scale is on that gauge?

[hemi43]

Originally Posted by mister.freeze

This is where my temp always has been before messing with the condenser.
I removed the condenser to take the fan off of it and ran around with the new shroud. Not as cool as it used to be! Cooler than with the condenser and no shroud, though. So I took off the shroud and am back to square one with just the fans on the radiator. As stated previously, max flow should be at highway speeds, and it is. In the past, I could turn off the fans at highway speeds and stay cool. If I forgot to turn them back on and got hot at at a stop or in traffic, turning them on would bring me back down to the pictured temp. Soooo... I'm going to try mounting the condenser up against the radiator with no condenser fan and no shroud. I think the shroud was hindering my highway flow, but improving my low-speed flow. If this doesn't work, I'll try mounting the condenser FARTHER from the radiator and using it's supplied fan to isolate it from the radiator. Thoughts?

As I said in my previous post, the condenser needs to be close to the rad. If it isn't you will create turbulence between the two and you will have "dirty" air trying to go through the rad.
Break out your wallet, get an aluminum rad and get an off the shelf fan/shroud properly sized for your rad and you wont have cooling issues.
Also, ditch that pusher fan, they don't work.

[beater6.0]

One thing to check. look into Rad and look and see if the core has built up mineral scale blocking passages.

[mister.freeze]

yes, I can throw money at it and all that. Thanks, but that's not the issue here. The point was the drastic difference adding the condenser that came with the kit made.

I will remount the condenser, close to the radiator, without it's own pusher fan, and see what that does.

I do have a thermostat and have thought about changing it, which I may still do. IIRC, the coolest one is 185 degrees?

The core is fairly clean on this brass 4-row radiator. Are you suggesting that if clogged up, it was on the edge of cooling, and adding the condenser pushed it over the edge?

I always thought the gauge read kinda low. The previous temp sensor I had read much higher, but had to change it and this is what the new one gave me.

[beater6.0]

Yes it could be clogged and you put it over the edge, you could use a temp gun or thermal imager to check temps. also a old school radiator shop should be able to flow test your rad. Another thing place a buisness card in front of your rad and condensor to make sure you have enough flow. Condensor need good flow to keep head pressures down and ac working good