2015 ford fiesta SE, 1.6 four cylinder motor, automatic. 53,000 miles.
AC has had an issue with going warm then cooling again for the last 2 years. I have been unsuccessful in finding out what the problem is as well as the car repair shops I’ve taken it to. I'm tired of dropping money with no resolve.
I am mechanically inclined and have been working on cars for 45 years.
First time the air went warm and then cold, I checked the Freon pressure and got 35 on the low and 220 on the high side. No red flags here. Compressor was always engaging.
Warm cold, warm cold, full charge, what is causing this I wondered.
After looking for leaks, finding none, I start the process of elimination.
Changed the low/high pressure switch. Didn’t fix it.
Both cooling fans come on when you turn on the AC.
I could accelerate and it would start to cool again while driving, the condenser wasn’t dirty or blocked, but I washed it anyway. I also changed the cabin air filter and the internal ambient temperature sensor, didn’t fix.
I replaced the AC control panel inside the car, that didn’t fix the problem.
Evacuated the system, pulled a vacuum and refilled to proper Freon levels, didn’t fix.
Compressor is engaging, doesn't make any noises, low pressure line gets cold and chills your butt real quick when it works.
One day when it did its warm cold warm and stays warm routine, I pulled the pressure again. This time low side was 120 and the high side was 250. I figured, OK the compressor is taking a crap, bad valves maybe. I shut everything off and went to bed as it was late.
Next day, I go to the store, I hadn’t shut off the AC controls and the darn thing was blowing cold again!!!
I figured it was a sticky expansion valve as the compressor was clearly working.
I evacuate the system, I change the expansion valve, I pull a vacuum, refill freon to manufacturers specs, doesn’t fix the problem.
Cooling now stopped completely. Now compressor isn’t engaging at all. I check the connection at the compressor, no juice. I check the AC relay under the hood, it’s not engaging. I swap relays out to check the relay in another slot, relay is good, it clicks and engages, but not in the slot where it is supposed to be. No juice to relay in engine bay. I check the climate control fuse, it’s good, all fuses inside the glove box and under the hood are good. So where is my power interruption at? I figured I would find a dead fuse inside the car, was actually getting happy until I looked at the fuse, it was good and I even put a meter on it to make sure the fuse was good. Sometimes they can look ok, but be bad.
My boyfriend says to by another AC control panel and I told him I have a new one in there. He said, new things can be bad. I had to walk away. All the gauges and buttons work just like my original AC panel. If two AC panels still have the same issues with the AC, WHAT ELSE CAN IT BE??? I’M GOING NUTS HERE…
Maybe it’s because the car isn’t painted RED………..I have no clue…….anymore.
Beam me up SCOTTY.............
You know the problem. You already figured it out but then you went to bed and woke up the next day and the AC worked again.
Gotta be the check valve in the compressor. It could have been the expansion valve but you already replaced it.
Your troubleshooting is impressive. You covered all the bases. I think the intermittent issue threw you for a loop when you landed on a bad valve in the compressor, but then woke up the next day and the AC worked
No reference was made to the "no power" to the AC relay in the engine compartment. I'm kind of old school, and since there is no problem with the glove box fuse panel, I'm at a lost as to the "no power" supply to the external ac relay.
You measured a "low side pressure of 120 psi". The AC can not function with that