Hey guys, I've searched all the previous posts, and nothing really seem to fit my problem. The AC just started blowing hot. Went to work, the AC was blowing fine. Nice and cold. Ready to leave work, and the AC was blowing hot. Stopped by and had the AC checked, they put the gauges on it, and the system was full, no leaks. The compressor was cycling on and off. What could cause this?

 

might not having enough air flowing through the front. try driving on a highway and see if it gets cold.

 

What was your high/low pressures?

 

The gauges read equal pressure on both sides. 100 over a 100. That means new compressor.

 

I had this happen in my 4Runner several years ago and it turned out to be a relay that senses when the car is overheating and cuts the A/C off. The sensor was up against the fire wall and was hard to get to. Don't know if this is your issue, but the symptoms were identical.

 

Checked all sensors and relays. Everything narrows down to the compressor.

 

your pressures are wacky, the low side shouldn't be at 100....should be someplace around 50ish depending on the temperature outside. the high side should be somewhere around 145-155. who told you 100 over a 100 means a new compressor. BTW this isn't a cholesterol test, readings on the ac system aren't anything over anything...

who got you these pressures?

 

Well, my explanation is a bit lost in translation from what the AC guy told me. What I do know is I was told the same thing first by the Lexus dealer. I was also told that the expansion valve is clogged up and full of crap.

 

All I did to mine when it happened one day was relieve some of the pressure and recharged the system.
Try that. Usually a 20 job if you perform your own work. Tool at auto zone is around 20-25 bucks

 

well if the compressor is running, the system shouldn't ever be equalized. it sounds like the compressor isnt running at all, is this the case?

i hope by relieving the pressure, you didn't just vent it off into the atmosphere...that's a serious no no. the proper and legal way to do this is to recover some of the freon through a recovery unit into a recovery tank and then vacuum down the system and recharge the unit using gauges not the auto zone charging can with the red/green area on it (or whatever they have)

 

Im having this same issue with my gs4. When the a/c works, it's cold as ice. Sometimes it works, sometimes it doesn't. Sometimes turning the temperature to 65 will kick it back on, sometimes it wont. It'll blow cold, then all of a sudden it will blow hot. Compressor SEEMS to be cycling during both temperatures. I had it evacuated and recharged, and all of it was there.. so no leaks. I havent had gauges on it tho, since.. you guys think compressor? I was hoping ambient switch? Sunload sensor?

 

how could you possibly have recharged it if you didnt put gauges on it? how do you know it has the correct amount in it without putting gauges on it?

 

The keyword there being 'since'. It was done at work, on the dealer a/c machine.. but I haven't had guages on it since then.