I turned my A/C on today, and almost cratered my engine...
 

My AC has never blown cold. Well, I live in Dallas, and it gets pretty warm outside. Any car I ever had I never used the AC much and just rolled the windows down, but my driver side window regulator is broken and I cant roll it down.

Anyway, today I popped the cap off the low side line and pushed the valve stem with a pen and there is definately pressure inside. Knowing this, I decided to turn the A/C on today and go for a short drive to see if the car moving would make any difference. The air got a tad cooler, but some strange things happened, which i will list below.

1) I could hear a noise in the cabin from the get go. Like when you nturn the A/C on at first in most cars, you hear a slight hiss from the evaporator and it quickly goes away. It was continuous in this case.

2) Even though the air was slightly cooler, it wasn't by much, just maybe a few degrees cooler than outside.

3) My engine started to try and overheat.

I was driving for only a few minutes and the noise in the cabin started to get quiet and I see my temp gauge at 50% (I have an S5, 50% is a smidge hot). I have the car some gas and it climbed to 55% and I immediately shut the car down. I turned the A/C off and started the car back up and the temp quickly plummeted back to 45% where it normally is on the gauge. I also went on a drive tonight for an hour and a half without the A/C and it never overheated.

So, my question is...what the fuck just happened?

1.) Don't know, replace your evaporator?

2.) You could have a crappy condenser.

3.) Of course, you put more load on the engine and it's going to get warmer, but maybe your cooling system isn't up to snuff.

make sure the a/c compressor isnt hanging up, make sure all your cooling compnants of the engine is working correctly, like your fan isnt leaking its fluid out and what not. the hissing is normal. sounds like your charge is to low. recharge it and i bet it will be cooler. only problem is that r12 is really expensive. you can convert to r134

well when the a/c is on the condenser will get warm, that's normal. now when the fan draws warm air from the condenser through the radiator it's not going to cool as well as if when a/c is off. the problem is the cooling system, maybe debris in between radiator and condenser? lots of crap gets in there and inside the fins of both cores too.

Does your electric fan come on? Its the one on the front side of the radiator that is used with the a/c

I have just a clutch fan. The condensor is stock and my radiator is brand new, so the rad isnt clogged up. before putting the new radiator in, I sprayed the condensor out real good and it isnt clogged either, I double checked today.

If the temperature system is vacuum controlled, which im not sure of, it could be a cracked/broken vacuum line, as to why its hissing all the time.

On some cars, the system has to reach a certain temperature before the computer opens a check valve to make sure the AC is blowing cold ENOUGH air, in most cases, your normal vent will blow slightly colder air than outside on its own without AC, so if the car is equipped with a check valve, it may not be opening at all due to low coolant.

As for overheating, make sure nothing is wedged between the rad / condenser, also make sure your clutch fan is actively turning when the AC is turned on, make sure the compressor isnt locking up the belt/pulley system and that it is infact turning when on.

Also the couplers and such for converting to 134a are cheap, but in my opinion 134 is just a giant fan, at least compared to r12 that would freeze you.

you may not have enough gas in the system

What happened to the electric fan?
Need to put gauges on to see what the pressures might be, but the electric fan will keep additional air flowing over the condenser/radiator when the compressor is energized.

Heck ya you need A/C in Dallas!

Ok, first of all, 50% (the gauge pointer is horizontal) is not hot on an s5. That's where they run with a normal thermostat. I have an actual temperature gauge with the sender in the thermostat neck. My 90 vert oem temp gauge pointer stays horizontal, 50%, from around 185* up to 235*. Your temp is NORMAL. Unless your pointer has begun to climb up above horizontal, your temps are A-OK.

Secondly, your refrigerant is probably low and it may be contaminated. The hissing is non-condensed gas flowing through the expansion valve. You should have nothing but liquid there, so you are low or you have non-condensables in the system. Don't run the system like this or you will kill your compressor. I can help you with it if you would like, and restore it to proper operation with R12.

PM me.

he has just a clutch fan. All my NA FCs only had clutch fans and I never had a problem with the AC.

My gauge has never moved above 45% except for that time, and it scared me to death.

Rob:
First off, I was agreeing with you, but the icon was dropped.

I was mentioning the electric fan for additional cooling, not necessarily for air movement over the condenser, but it certainly helps. That’s why it’s there. Had a Buick a few weeks ago that had a problem, the electric fan wasn't working, neither was the A/C. Fixed the fan, fixed the A/C.

Only turbos and cars with automatic transmissions had the extra electric fan. None of the manual NAs got them. And the S5 temperature gauge is horrible. It basically has 3 settings: cold, warm, & melting down.

no worries, seems you asked about his electric fan, I think we are mis reading each other's post.

My vert when it was stock S4 had KICK ASS air conditioning!