AC compressor kicks on/off after conversion to R134

**N2ORBT** · 05-19-04, 03:33 AM

Hey guys, newbie here. Not too much into performance but you guys seems very knowledgable about hondas so I had a ? for you. I own a 90 civic sedan and after converting to R134 my compressor kicks on and off every 10 to 20 seconds. It's irritating as hell when driving around cuz I can feel my car being robbed of power everytime it kicks on. I took it back to the guys that did the conversion yet they said it's hitting it's desired temp. so the compressor kicks off. Now I've never really heard of this happening to auto AC. I'm thinking it's a fuse or relay. It runs really cold but it never did this before. So my question is during the process of the conversion could something go wrong to cause this or is he blowing freon up my a$$?

**FourthGenHatch** · 05-19-04, 08:39 PM

When you convert to R134a you are supposed to get new sensors/switch which operates with the temp changes R134a does as opposed to freon or R12. I wonder if they ever put a new switch in because it might be switching on/off at the wrong temps now.

**tilt** · 05-21-04, 11:15 AM

check if you are over or under pressurized. i just did a retrofit on my crx and it doesnt do that.

**ZiviCase10287** · 05-21-04, 03:37 PM

i just did a R12 - R134a on my 92 accord lx and it turns on and off with my button! never heard of that... they ****ed something up.

**m735is** · 05-31-04, 01:39 PM

I installed A/C on my 92 Civic from a wrecked car- everything was plug and play. I had it evacuated and recharged with 134- it was switching on and sucking all the power from the car, like I hit the brakes-very annoying when shifting-looked like a new driver. I let out some pressure and it got alittle better.
My other 92 Civic had A/C in it, there is a blue relay or switch mounted to the top of the core up front that my retrofit Civic didn't have.
Is that the 134 switch that is mentioned above???

Need more info on this switch.

I would take some pressure out and see if it cycles less.

**mohamed_ibrah** · 05-31-04, 01:52 PM

Originally Posted by m735is

My other 92 Civic had A/C in it, there is a blue relay or switch mounted to the top of the core up front that my retrofit Civic didn't have.
Is that the 134 switch that is mentioned above???

Need more info on this switch.

I would take some pressure out and see if it cycles less.

High pressure cutoff switch...it's supposed to be in place to replace the high pressure relief valve found in R-12 systems and is a minimum requirement when doing a retrofit.

Also A/C compressor cycle because of two reasons:
1) When the a/c system pressure reaches a certain pressure, it turns off to protect the system from over pressurization.
2) when the evaporator core reaches close to freezing point, it turns off so that a huge block of ice doesn't form on the evaporator and then block air flow.

When you place new refrigerant into a system from retrofit (especially R-134a) you're supposeded to use like 70-80% the amount of R-12 because R-134a operates at a higher pressure state. Your a/c shop is supposed to do a performance test by:
1) measuring temp of the air coming out the center duct (has to be a minimum of 20 degrees below ambient temperature)
2) Check high and low side pressure by hooking up a manifold gauge (the low side should be somewhere in the vicinity of 20-40 psi and high side should be something in the vicinity of 180-220 psi, of course these are rough estimates)

A good a/c mechanic is supposed to know if anything looks out of whack, sort of speak, and recommend the appropriate repair. It just might be the way the system is designed to perform by the constant cycling on and off. I know that my 2001 GOV Jeep Cherokee cycles like crazy, but the system blows out some damn cold air.