Question About A/c In Hot Weather

az'03Silverado · June 17, 2007

This truck is an '03 ECSB with the 4.8L. The weather just topped 110 here in the Valley of the Sun. I've noticed that the A/C gets slightly less cool when the truck idles for 2-3 minutes or so in this weather. The refrigerant is fully charged and it's done it since new. Once I give it some gas (approx 2000 rpm) the A/C cools back down. I'm assuming that this is normal for the extremely hot temps and limited airflow through the condenser. The question is this: Would installing a 9-10 inch flex-a-lite fan on the condenser with an A/C relay help this? Would it effect the airflow to the radiator? I know that a 9-10 inch fan won't cover the whole condenser but may remove a sufficient amount of heat to allow the A/C to function fully at idle. Any thoughts?

asepgrad98 · June 17, 2007

all r-134a refrigerant cars do that. you can thank the feds for banning r-12

ZZ327 · June 17, 2007

Its probably the compressor cycling. Do you have the button on recirc? A extra electric fan will probably cool it down a little more but I dont think it would be very much.

az'03Silverado · June 17, 2007

Yes, I have the recirc button on. In fact, I've noticed that when I don't, it will automatically turn the recirc on after a while.

That's interesting about the R-134. I was only a kid when R-12 was the norm so I don't remember how well it worked as opposed to the R-134.

Any solutions or just live with it? I guess it's just due to the really hot temps we get here. It works fine at idle when the outside temp is below 100. But it's been in the 108-110 range for a few days and I've really noticed it.

RobDarden · June 18, 2007

I did notice that in my 04 Colorado and 06 Silverado. The 07 does not seem to do that though. I don't know if they improved the system or if its because we haven't really had many over 90 degree days.

frdfandc · June 18, 2007

Reason that your A/C doesn't seem to cool enough during long idle periods is due to the lack of air flow across the condensor. Installing an electric fan will help out some, but not sure how much.

Air needs to flow across the condensor to cool the R-134a after it has been compressed by the compressor, which causes heat.

C & A s Dad · June 18, 2007

Sam, this is a very common problem with may vehicles with elect fans. I know yours does not have e fans but you may want to have your fan clutch checked. I live in Mississippi and our temps are not quite what you are seeing but my Yukon XL stays ice cold whether driving or at idle.

With vehicles with e fans it is all about the air flow. We suggest two things.

1) There is a chemical additive called Sub Zero made by Quest that will help. It is friction modifier that helps the compressor do a better job. I am not big on this type of stuff but it dropped my vent temp on my Dodge Caravan at idle by 4 degrees. Not a lot but it helped. There are other companies that offer this type of product but from what I can tell Sub Zero is the best. You can get it in a 4 oz can (part # 342 D) that contains 2 ozs of Sub Zero and 2 Ozs of 134 A. It also comes in larger containers but they simply contain more 134 A and still 2 ozs of Sub Zero.

2) You can make sure there are no air leaks around your condensor. Use some foam or other material and make sure that all the air that comes through your grill is being pulled through the condensor and radiator. I am not sure on your truck, but some vehicles are not sealed very well in this area letting a lot of air go around the condensor.

You can check out the Sub Zero but as of today, we have never had an issue with it.

az'03Silverado · June 18, 2007

Thanks for all of the replies. I'm pretty sure my fan clutch is good. When I give it gas I can hear the fan screaming up there which tells me it's engaged. I'll look into some of that Sub Zero. I've got a good CarQuest dealer close by that I've used for years. I'll also check the seal around the condenser. Thanks again everybody.

C & A s Dad · June 18, 2007

If he does not handle the Sub Zero, tell him it is on page R 93 of his 2007 Service Line Catalog. You can see 3 or 4 size options there.

If anyone here has heard of any issues with Sub Zero, please let us know. Again, to date, I have never had heard of an issue with the product and it does work.

az'03Silverado · June 19, 2007

Awsome, I'll give it a shot. So, the verdict is that E-fans won't help much?

plainvanilla · June 19, 2007

Reason that your A/C doesn't seem to cool enough during long idle periods is due to the lack of air flow across the condensor. Installing an electric fan will help out some, but not sure how much.

Air needs to flow across the condensor to cool the R-134a after it has been compressed by the compressor, which causes heat.

The R-134A goes into the condenser as a gas it needs cooled through the tubes in order to condense and turn into a liquid again so it can go through the metering device (orifice tube or expansion block) and then as it goes into the evaporator at a very controlled rate, it turns back into a gas and when it does it gets very very cold. The blower fan up in the dash blows air through the fins of the evaporator core and bob's your uncle, cold air

The cooling of the fan or ram air if your driving aids in the condensing, it's simple really, you put a cold glass of ice water down on a table and the cold surface of the glass condenses the moister in the air into liquid and the glass gets all wet on the outside, same principal. I would say install a second condenser fan but don't expect big results, it will help in drive-thru and stuck in traffic situations. You need to use a relay and you can use the clutch cycle switch as your trigger to close the relay and automatically turn on your fan. It all could cost $100.00 for everything so just weigh out the benefits vs cost

good luck with it.

az'03Silverado · June 19, 2007

Thanks for the input. So, say I do install an electric fan. Should it be a pusher or puller? I think there's enough room between the condenser and the radiator to put a puller. Will this effect the airflow to the radiator? I'm thinking not but I could be wrong. Any thoughts on that? I think a puller would be more effective and there's more area to install a larger fan.

C & A s Dad · June 19, 2007

I have never seen that done but it could work. Just not sure it would have enough airflow around it to do what you want. I am going to have to let someone else offer some advice here.

I know it sounds extreme, but Hayden also makes a "mister" that can be installed in front of the condensor. It consists of a fresh water tank, a pump and some fine mist nozzles that allow you to spray cool water into the condensor whenever you want. I think one could be made pretty easily also.

ZZ327 · June 19, 2007

I would check out your AC charge before you do anything(40-45 PSI low side running).

If you are going to add a electric fan as extra, put it on the Front of the radiator/condenser and make it a pusher. If you are thinking of totally replacing what you have. Take your original engine fan off. And add a big electric or dual Flexalite fan ( on the engine side of radiator) as a Puller.

R134a has the exact same cooling properties as R12. There isnt a difference.

One more thing you definitly want to check out is your Cabin air filters!!! That could cause your problem

plainvanilla · June 19, 2007

R134a has the exact same cooling properties as R12. There isnt a difference.

A bit off topic but the big reason we don't have R-12 anymore is that Dupont's patent was set to expire, so they pushed to have it outlawed because they no longer had the means to produce a product nobody else could.

Once again, it was more about politics and money than saving the earth.

sorry for the hijack

Back on topic

I agree about making the second fan a pusher and you should only need about a 14 inch one or so.

that Hayden mister system sounds interesting also, I actually built one similar to that for my house AC unit