Do your A/C lines frost up?

[jpanek]

The ones in my engine bay do. The suction line and accumulator get covered in condensation and then frost in minutes. Condensation I can understand, but I thought the compressor was supposed to cycle off when the evap got below 35 or so.

Another thread here has water from those lines blowing toward the opti. This is my main concern right now.

 

[jmccloud]

Frost

My lines do not frost up (not that I've noticed anyway). When I bought the car, there was a shorted transistor in the control head (C60 manual A/C) which caused the compressor to always run except when the low pressure switch cut it out (cool weather). Even so, the lines didn't frost. My '95 has 134A.
Perhaps your refrigerant charge is low??
Hope this helps

 

[jpanek]

I've got the elctronic climate control, and it does turn off when you hit the off button. When the car is first started, it is in auto mode, and then the a/c clutch is always engaged even if the temperature request is high.

I don't think the charge is low, as it did cool the cabin very well on a hot Florida day when I bought it.

 

[jmccloud]

another possibility

Could be that the low pressure sensor isn't cycling the compressor clutch. I'm not sure how the auto temp control A/C works but on a manual A/C, if the cabin air temp is too cool to evaporate enough refrigerant (in the evaporator in the dash), then the pressure drops and the low pressure switch cuts power to the clutch, disengaging the compressor.
The low pressure switch is in the suction line (the fat one) near the blower motor (passenger side near oil dipstick). It has a connector that can be removed by pulling a keeper (keeper is brown I think). Then the clutch should not pull in. If it does, the clutch is stuck. That might cause freeze up too.
Hope this rambling answer helps.

 

[jmccloud]

Another possibility

There's also a relay between the low pressure switch and the clutch. Could be the relay's stuck. The relay is behind the passenger side front wheel. In a C68 (auto air) if you have an automatic, there will be one relay. If you have a stick, there will be two relays, the other for the 2nd 3rd gear blockout. I don't know which is which. Removing the A/C relay should disengage the clutch.

 

[alan ream]

You didn't say if the 35 was temperature or pressure. However, my experience indicates that you're low on charge. I don't know if you have refrigeration gauges or not, but if you do, the low side should never go below 35# even when you're running the engine at about 2-3K rpm.
Hope this helps, let me know.

 

[HPG]

Usually any refrigeration unit that will frost up the suction line is low on gas or has poor air flow. I guess you have R134. Buy the kit with the gauge, it's color coded and will tell you if the system is low, It's very easy to use and add gas. .

 

[jpanek]

Thanks for all the replies! I'm concentrating on geting the title/registration/taxes etc done right now. And with the colder weather A/C is second priority to getting the heater core fixed. But I will need A/C for defrosting the windshield and to run the compressor occasionally to keep the seals from drying out.

The 35 I mentioned was my guess at evap air temp. I'll get the guages on it tomorrow and let you know what I find. I have a hard time beliving the charge is low since it cooled so well down in Florida. The day I inspected it must have been in the mid 80's and sunny, and the A/C was just great.

Also, when the OBD computer was hooked up, the vette told us the refrigerant pressure was 69 psi when not running, and when A/C was turned on the pressure changed (up or down I can't recall).

The previous owner complained of a water leak here a year or so ago. Perhaps he was icing up the core and when that melted it looked like a water leak. Hopefully that's an easy sensor changeout without taking the dash apart.....

 

[jmccloud]

Luck

Wouldn't it be a great stroke of luck if the previous owner disconnected the heater core because the evaporator was icing, thawing and ''leaking''?
When the titling, etc. is over, park the car in the shade with the A/C on and set to modest temperature. Raise the hood and watch for several minutes. If you have a set of gauges, read the suction pressure. If the compressor doesn't cycle, the difficulty is in the control (bet that's where it is).
The auto a/c has self diagnostic capability, including detecting low refrigerant via sensing too frequent compressor cycling. If a relay is stuck, the computer probably won't know it. A GM service manual lists codes, etc.

 

[oldace84]

Isn't that normal.
If not what could be wrong.
Mine drip when I turn the car off.
Do yours?
tony

 

[rrhayden]

It Indicates the system is low on charge. The referegent is beginning to expand and boil before it gets to the evaporator. In my case it was wetting the opti and causing a miss, and surge