Running warmer after A/C recharge?

JAFO

Registered User
I've noticed that my car has been running remarkably cooler this year, even in the heat of the day. Straight up needle, rock solid. But, my a/c was less and less effective, barely working. I had the a/c checked out, no leaks, compressor is running like a champ. No problems that they could find. It was 2lbs low on freon, so, rather than convert to less effective freon, I had it recharged with R12. It didn't work when I picked it up, so they "put more vacuum on it" and it blows like friggin' ice now without even being all the way down.
What I've noticed since then is that the car runs a little warmer. Not alarmingly warmer, but it gets up to the middle of the "M" (wish there were temp degrees on the gauge), where it used to be straight up. Does the work on the a/c put more drag on the compressor causing the heat by slowing things down? I wouldn't think it would do that, or at least not enough to raise the temp.

Is that normal?
 
JAFO said:
I had the a/c checked out, no leaks, compressor is running like a champ. No problems that they could find. It was 2lbs low on freon, so, rather than convert to less effective freon, I had it recharged with R12. It didn't work when I picked it up, so they "put more vacuum on it" and it blows like friggin' ice now without even being all the way down.
The leak is there, they just didn't find it. A tight system will never loose refrigerant. 2lbs is quite a LOT as there are only 2.5 to begin with. Did they change any Orings and add some mineral oil? Loss of oil and water contamination in an r12 system is what kills the compressor. Look at where the spring locks hook up and see if they have a dirty oily residue around them. If so, there's your leak.

Does the work on the a/c put more drag on the compressor causing the heat by slowing things down? I wouldn't think it would do that, or at least not enough to raise the temp.

Is that normal?
Usually, running the A/C around town will cause the temp to drop slightly. Thats because the fan kicks in automatically with the A/C on. But as for your problem, it sounds like you could be low on coolant. When the car cools, take the radiator cap off, undo the burp cap which is the white cap to the right of the supercharger with a bolt in the middle of it, and refill the radiator. Then fill the overflow bottle to the cold level. put things back together, and watch the level in the bottle once you've driven around. Keep it refilled when the engine cools. Do this for a few days and see if things improve.
 
Shouldn't be low on coolant, but I'll check just in case. May all be my imagination.
Thanks!
 
Think of cooling as simply an absence of heat. So now that your evaporator is cooling more, that means it is transferring more heat to... the Condenser. Now that the condenser is carrying more heat to be exchanged with the air flowing over it, the air now flowing through the condenser to the radiator has less capacity for removing heat from the radiator. This is because the condenser is now using up some of the capacity where before when it wasn't so cold, it wasn't.

At least that is the Garage Logic theory using 7th grade physics and Thermo-King refrigeration systems training.
 
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That makes sense. Since the a/c was less efficient at getting rid of the heat (cooling) the air flow passing through the radiator was cooler making it more efficient. Odd trade off, but it isn't running super hot, just a little warmer. Seems like there might be room for improvement here, but probably not worth it.
 
Bill, I had to charge mine last weekend, it was a pound and a half low and this week i am definitely running hotter. I was going to post on the issue too ! I was thinking along the same lines as Mike8675.....Compressor is now running consistently and creating warmer under-hood temps,and coolant was the first thing i looked at,and am going to keep an eye on. I need to quit procrastinating and wire up some cool fan switches. Does anyone know what the temp is (in degrees) when the OEM guage is on the M ?

Jeff
 
What I would do is watch the gauge for when the low speed fan trips. Then you know that's right around 220 degrees.

Make sure your air dam is still in position under the front of the car. That helps direct air into the radiator. I've still got to get mine put back on.
 
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