ac intermitent

AC was intermittent today, had the comp, drier replaced laced summer, acts like it needs a recharge . Then today not a thing just the hot air , ran with the windows open for bit (all the switches off ) Was too much, hit the switch & had much cooler air . Thinking now it may be the switch itself . Has anyone had that panel rebuilt & where can I get it done ? My booster heater also went out last winter . Thanks
 
AC was intermittent today...
I'm sorry to hear that. Let's see what we can do to help.

...had the comp, drier replaced laced summer...
Why?

...acts like it needs a recharge...
Air conditioning systems do not act. What is it that you are seeing, hearing, feeling, and/or smelling, that is causing you concern?

Then today not a thing just the hot air , ran with the windows open for bit (all the switches off ) Was too much, hit the switch & had much cooler air .
Can you explain that just a little bit more please?

Thinking now it may be the switch itself .
Why?

Has anyone had that panel rebuilt
I have not. Were you taking a survey?

My booster heater also went out last winter .
Thank you for sharing that.
 

vanski

If it’s winter, I’m probably skiing..
hot air as in ambient hot air, or, hot air like engine hot air?

if just ambient hot air, I would GUESS the internal relay on the ATC has lost its contact and you need it reflowed.. can be done diy if you know what you're looking at and are good at soldering (small solder contacts), or take the ATC to an electronics guy who can put it under a magnifier to see the broken contact(s) (should be around $50).
 

Dougflas

DAD OWNER
hot air as in ambient hot air, or, hot air like engine hot air?

if just ambient hot air, I would GUESS the internal relay on the ATC has lost its contact and you need it reflowed.. can be done diy if you know what you're looking at and are good at soldering (small solder contacts), or take the ATC to an electronics guy who can put it under a magnifier to see the broken contact(s) (should be around $50).
Common problem. If not bad now, it will be. I would have this done whether it is bad now or not.
 

Midwestdrifter

Engineer In Residence
A common cause of no compressor activation (when charge is good). With a good scanner check the AC system pressure with the engine off, should be about 95psi in summer temps. If not you have a low charge or bad sensor. Then turn the AC on. Does the clutch engage? Check the clutch status with the scanner. If it indicates the clutch is on, then its probably the relay solder points on the board (behind the temp knob). Fairly easy fix you you can use a soldering iron.

This failure causes the Clutch to become intermittent. Often Letting the dash cool down, then restarting later in the day will have the AC work, at least until you turn it off.

Edit:
See P-T chart here, and my post below.
https://www.forane.com/export/share...ls/forane-134a-pressure-temperature-chart.pdf
 
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vanski

If it’s winter, I’m probably skiing..
To not guess.. simply hit the button and see if the +12v wire going into the compressor lights up

That is, that’s how it gets it's signal; +12v on that wire when the AC button is pushed. Now, if the system has low pressure, the atc wont allow the signal.
 
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rollerbearing

Well-known member
A common cause of no compressor activation (when charge is good). With a good scanner check the AC system pressure with the engine off, should be about 45psi in summer temps. If not you have a low charge or bad sensor. Then turn the AC on. Does the clutch engage? Check the clutch status with the scanner. If it indicates the clutch is on, then its probably the relay solder points on the board (behind the temp knob). Fairly easy fix you you can use a soldering iron.

This failure causes the Clutch to become intermittent. Often Letting the dash cool down, then restarting later in the day will have the AC work, at least until you turn it off.
Check me on this (I am rusty and not had much coffee yet) but 45 PSI sounds more like the pressure expected for approximately 50F evaporator temp. That is - the motor is running and the compressor is turning. At, say 100F, the vapor pressure of 134a is around 124 psi (gauge) - what I think you would see with motor off and a charge with at least some liquid phase.
 

Midwestdrifter

Engineer In Residence
Your right, I was thinking of a different refrigerant.

Here is the P-T Chart for 134A.

https://www.forane.com/export/share...ls/forane-134a-pressure-temperature-chart.pdf 85F is ~95psi. If you see values well below the P-T chart for the ambient temp (before turning the AC on). THen you have essentially no charge. As long as there is some charge, the pressure will match the P-T chart, which is valid as long as there is some liquid refrigerant in the system.
 
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