AC temp varying with outside temp....

[SHOtimer]

So, after installing a new AC system (compressor, accumulator, orfice tube) and moving to a much hotter climate I have a few questions for the experts regarding my AC.

In my home town of Salinas it wouldn't get above around 75 and my AC (this new system) would blow ice cold. During my trip down here while drivng through the desert between 75-85mph with tempatures around 90-100 the AC was nice and ice cold.

Now, if it is evening or morning around here and in the 70's at idle at a light or around town the AC will blow nice and cold. If it is in the 90's-100's at idle or around town the AC is significantly warmer, not nearly ice cold, but cool (cool enough that I know it can get colder and I want it colder). If I get onto the freeway and get moving it will cool down more but it seems that if I want it nice and cold and it is in the upper 90's and 100's that I need to drive anywhere above 55 for an extended period of time.

So, is this just wishful thinking that the AC be ice cold all the time no matter engine speed or outside temp? Or do I need to do somemore :jab: to my AC system?

As a note, the sytem does not cycle excessively and the the clutch always engages when it is turned on.

Thanx, Doug

 

[SHO#7]

I do not know the specs for what a system holds, but you may need to add some more freon. Just a little low will not cause the compressor to cycle too much. But may affect performance.

The only other thing that I notice in your post is that you noted it to be cooler when traveling at a constant highway speed. Are you sure that you fan(s) are turning on. No fan will mean the condenser will not cool the freon properly.

I am by far no AC expert. Hope it helps though. Good Luck.

 

[SHOtimer]

The fans are operating properly, whenever the AC is on they are on also.

Doug

 

[Rob94]

Do you have a set of gauges for your AC system? It would be very helpful if I knew what your pressures were, both static, and with the AC on. At this point, I can only speculate that you may not have a full charge of refrigerant.

 

[fred79]

ac should only be able to cool at maximum efficiency about 20* below outside temperature so keep that in mind. also the fans may not be able to pull enough air and require the air flow from higher speeds to cool the condenser, you could also check to make sure the condenser isn't clogged with leaves and road dirt that would lower efficiency.

 

[SonicRiot]

Sounds like normal operation. The condensor is in the front of the vehicle for a reason... it needs airflow to change the refrigerant from a high pressure gas to a low pressure gas. When you are idling on a very hot day, there is no airflow through the condensor, thus yeilding a more inefficient refridgerant system.

Also, the com[ressor is designed to optimally function at crusing speeds (1800-2800 RPM). When you are at idle, the compressor is working overtime because it is not spinning as fast, thus yeilding an inefficient refrigerant system.

 

[rangerj]

I agree with Rob94. We need to know what the pressures are in order to be helpful. It would also help to know what the temperature of the air coming out of the center dash vent is. An A/C thermometer is an inexpensive tool, but provides important information about how well a system is working.

A system that is working well should be able to produce about a 40 degree difference between the A/C air temperature and the outside air temperature. So if it is 100 degrees outside the A/C air should be about 60 degrees. At 75 degrees the A/C air will be about 37 to 40 degrees, which would feel ice cold.

You say your fan is working, but is it working efficiently? The electric fan motors slow down with age. The air flow over the condenser is vitally important to the operations of the A/C. The fact that your A/C system works better when you are moving makes me think that the fan may be a contributing factor to your problem. food for thought, rangerj

 

[SHOtimer]

Well, I am not near home and don't have any of those tools and am not really inclined to let these people start pokin around on my SHO. I am going home at Halloween and will go by the AC shop that charged my system and helped me with it a bit, and have them check the pressures along with the vent temperatures. When I had it charged the low side was 35 and the high somewhere around ~165 (might have been 175). The temp out of the dash center vent was 17 degrees, this is with an outside temp of about ~55-60 degrees. My fans are blowing quite hard, I was pokin around today and when they turn on it is a blast of hot air traveling rather fast (these are the rad fans of course). The car stays right on the L with the AC on and never goes above so I assume that the fans are working to their optimum output. But, if they weren't how would I go about testing that?

When I speed up it isn't a dramatic change but I can tell if I really pay attention, if it is on for a while to 10-15min I notice it gets colder over time also. So, assuming I have a full charge, which I will check, this may be normal activity for sitting at idle in 100+ degree weather?

I guess it makes sense that the AC can't do at 100+degrees what it can do at ~70 eh?

Thanx, for your help guys

Doug

 

[rangerj]

When you are sitting in 100 degree temps your "under hood temp" is in excess of 200 degrees. Check you EATC system. Is you EATC recirculating the cold air, or are you trying to cool 100 degree air all the time. Just a thought.

It sounds to me as if your A/C system is in good shape, including the radiator fans. Maybe you are expecting too much from the system! How do other folks' systems work in the same climate?
rangerj

 

[SHOtimer]

Well, the EATC is cooling the 100 degree air when it is on auto correct, and recooling the interior air under MAX AC correct? I assume that is what it is doing, do I need to check that? It does get a bit colder after awhile on MAX. Well, since I just replaced the sytem I guess I might have been expecting that it work wonders and be freezing all the time, no matter the outside temp. But, then unfortunately reality sets in. I didn't really consider that the underhood temps would be so extreme but it makes sense, tha tthe AC can't do that good of a job when dealing with those temps.

Thanx, Doug