Is there a direct correlation between engine temp and a/c performance?
Thread Starter
Drifting
Joined: Jun 2004
Posts: 1,881
Likes: 9
From: staten island ny
Is there a direct correlation between engine temp and a/c performance?
Is there any direct correlation to engine compartment heat and a/c cooling properly. It seems that when I first start my car the a/c blows nice and cold but as the car heats up my a/c gets warmer. My engine will get as hot as 210 deg, another issue I'm workin on. I even went as far as ordering the $60.00 glass top shielding insert from Mid America to keep the sun from cooking the compartment and it helped but only a little. My system was empty, from a leak I assume, when I bought the car. I did a 134 conversion myself, never had it evacuated, just 2 cans or so of 134. AFter about 45 mins to an hour on the road it's gettin warm in the cabin and the air is not blowing as cold. Never put a thermometer on it to get an exact temp. I even tried insulating some of the a/c lines under the hood. Also 2 1/2 inch exhaust, no headers, no cat if it matters. Car is a 79 with a new gm crate engine, nothing exotic.
Thx, ESU.
Thx, ESU.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
I am suprised your a/c gets cold without evacuating first... Check to make sure the heater control valve is turning the hot water off to the heater. It is on the right fender-well, just under the coolant recovery tank. The a/c control turns it off when in the a/c mode.
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
The engine temp should not affect AC performance. Something else is going on if you see a difference in AC performance. Only in MAX AC is the heater core bypassed. In all other AC modes the heater core has hot engine coolant circulating through it. If your heater baffleing is bad that may account for the differences in your AC performance.
Le Mans Master
Joined: Jul 2005
Posts: 5,752
Likes: 4
From: Austin Texas
Prior to adding freon to an empty system, or doing an R-12 to R-134 conversion, all gasses need to be evacuated from the system by pulling a 30in. vacuum. (professional equipment is required to do this). Only then can you add the required amount of freon.
P.S....If you didn't evacuate, you may have moisture in the a/c system, which may be freezing up. this will stop the a/c from cooling.
P.S....If you didn't evacuate, you may have moisture in the a/c system, which may be freezing up. this will stop the a/c from cooling.
Last edited by big_G; Jul 23, 2005 at 09:22 PM.
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Race Director
Joined: Sep 1999
Posts: 11,360
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From: Plano TX
Not evacuating before charging is a big no-no. You may also have damaged the compressor or other parts by now.
In addition your system is also undercharged which leads to evaporator freezing.
In addition your system is also undercharged which leads to evaporator freezing.
Drifting
Joined: Dec 2004
Posts: 1,345
Likes: 3
Baffleing was probably a bad choice of words.
There is a swinging panel that allows adjustment of the temperature coming out of the air conditioning vents. If that part is damaged or not sealing properly when closed AC performance will suffer unless running in the MAX AC setting. That would NOT apply if you have a ball valve to stop the flow of coolant to the heater core.
QUOTE=ESU]I've isolated the heater core with an in line ball valve to shut it down. I dont know what "baffling" you mean.
ESU[/QUOTE]
There is a swinging panel that allows adjustment of the temperature coming out of the air conditioning vents. If that part is damaged or not sealing properly when closed AC performance will suffer unless running in the MAX AC setting. That would NOT apply if you have a ball valve to stop the flow of coolant to the heater core.
QUOTE=ESU]I've isolated the heater core with an in line ball valve to shut it down. I dont know what "baffling" you mean.
ESU[/QUOTE]
Racer
Joined: Jan 2003
Posts: 383
Likes: 0
From: Columbia SC
Originally Posted by PhotoVette1
You probably are freezing up your evaporator coil. Does your 'Vette make a big puddle after you park it in the garage?
I know cause after I did my 76's A/C system and added R12 my evap core will now turn into a block of ice if I leave it on MAX-A/C to long. And yse when this happens I have a really nice flow of ice cold water coming from the A/C box on the passenger side. It looks like it sprung a leak...
ESU you need to do all of the A/C related things or you will never get that system running correctly. Search this site for prior posts and do some reading.
I dont think the engine comp temp has anything to do with the performance of your A/C system. Mine is 100% bone stock (except for the 1996 Vette blower motor) and none of my A/C plumbing is shielded in anyway.
You also will need to look at the heater/ac box and make sure it has no air leaks cause hot air from the engine comp can come in and steal the cool air right.
And like suggested above turning off the heater core is a great suggestion, at least until you get the A/C running the way you want, then you can hook it back up again.
I hope this helps
