Magman

iTrader: (6)

Need some help with my 86 IROC-Z, 305 LG4, w/AC.

Last night I had the car idling in the garage (door open of course) and was raising the idle (so when the AC kicks on the car doesn't die) While doing this, I noticed smoke coming up from the fitting on the pass side, next to the radiator going into the (evaporator? small radiator part in front of the actual radiator, not sure what it actually is). The line goes from there back to the AC compressor and was extremely hot to the touch. Since I knew something wasn't right, I went to turn the car off. Back in the drivers seat, I smelled something burning inside from around the fuse box area and also noticed my heater fan wasn't working anymore.

I know I need to find and repair the wire that got melted inside but, did my AC compressor just die? Is that why the small line from it is getting extremely hot?

Checked it again today and within a minute of idling w/defrost on, the smaller line from the compressor gets really, really hot.

Let me know what you guys think and where I should look after I find/fix my wiring that failed.

Mdenz3

iTrader: (7)

How and A/C system works:
The compressor sucks in refridgerant and cmpresses it to high pressure (usually around 150-200 psi IIRC) because of its higher pressure its tempiture will raise signifcantly. Next the refridgerant travels to the condensor (the small radiator type thing infront of the radiator) where the air cools it and it condensates. The now liquid refridgerant now travels to the fixed oriface tube which restricts the flow of refridgerant through a tiny hole so the pressure drops, (usually around 30-35 psi) and because the pressure drops the tempirature also drops dramaticly. After the FOT (fixed oriface tube) the refridgerant goes to the evaporator inside the car where the heater fan blowing warm air across the evaporator cause the liquid refridgerant to evaoporate removing heat from the air. The evaporated coolant then to the accumulator where there is a desicant material to collect any moisture and the accumulator ensures the no liquid coolant goes to the compressor.(liquid wont compress and will destroy the compressor also moisture + A/C system = bad news) The radiator fan should be on while the A/C is running and the compressor clutch should cycle on and off not just run the whole time. (this is also how the cooling system works in your engine which is why you need to put a restrictor plate in if you remove the thermostat)
You said you saw smoke from the line, was there someing burning off it or was it refridgerant leaking out?
Other thing to check:
Will it blow cold air out of the vents?
On the line coming from by (not into) the large alumnum canistor (accumulator) then into the evaporator housing. At the connector there (where the FOT is) before the connector shuold be warm and after the connector should be cold. Is it?
After the engine has been off for a little while (so the pressure between the high and low side of the A/C system can equalize) unplug the electrical connector in the line with the FOT in it (not the connector in the accumulator) and check the resistance between the two pins with an ohm meter there should be no connection. (if there is either your prsessure is way to high in the system or the switch is bad causesing you compressor to run continusly and over pressure/heat the system.
I hope that explanation helps. If you need any more help let me know, and if you find a part you need let me know i just removed the entire A/C system from my car.

Magman

iTrader: (6)

Mdenz3 - Thanks for the AC 101!!

I've made some progress. I found two wires melted together in the heater control unit main connector. I replaced the connector and control unit from a different car and now I have heat/AC again. Blower motor doesn't work on high so I'm going to try a new blower relay tomorrow.

I checked the AC as stated above and yes, it does blow cool air, not cold but cool. With AC on, the compressor cycles on and off. When I switch to defrost, the compressor cycles once or twice more then stops cycling and the line from the compressor to the condensor gets real HOT, so hot, you can not touch it. Everything seems to be working though, I was just concerned it was running too hot and I was going to burn something up again.

So... when in defrost mode, is this line supposed to get scorching hot? And is the compressor supposed to stop cycling? If so, my system works great.

Also, there is no connector in the line with the FOT in it, just a servicing port. This is the line from the condensor to the evaporator correct? The only connector (besides the two on the compressor) is the connector on the accumulator. All other conectors are associated with the heating system (blower motor/resistor/blower relay). Thanks for the help!

Mdenz3

iTrader: (7)

There should be (but i am referancing a 91 system) it would be located below the accumulator where the line runs along the frame rail. And the line should be quit warm (about 180F i think?). If the compressor is cycling this switch should be good though. Does the tube after the FOT feel really cold or have condensation/frost forming on it? If you can't find anything else wrong you may want to take it to a repair staion and have them put a gauge set on it to check the pressures in the system.
The things that can cause a A/C to get too hot are:
Over filled with refirdgerant
Something blocking air flow over the condensor
Bad High pressure switch cause the compressor to run continuesly
Blocked FOT
Radiator fan not running