How long between AC compressor cycles?

[Wes F]

Hi all,

Anyone know what is the normal time between the compressor cycling on and off? I just got through fixing my AC (r12) system (no, I'm not crazy to do this in winter, I live in Hawaii ;) ), replacing a low pressure hose and expansion valve, along with the obligatory o-rings and drier.

Took it to a shop and had it evacuated and charged up, checked out ok with no leaks and I was on my way. Blowed ice cold, everything seemed fine, until I noticed as it was idling that I couldn't really hear the compressor going on and off like it's supposed to. I'm sure it should cycle every like 15-20 sec or something, and mine seems to just stay on.

If the pressure switch is screwed, will the compressor keep going until it completely overpressurizes the system, or is there a backup? I'm thinking I might have jacked up the pressure switch connections as I was trying to remove them - plastic over 18 years becomes a bit brittle, so parts of them kinda broke apart, but I thought I reconnected the wires ok. I dunno, do I need another switch?

Thanks for all your help, it's amazing how much I've done because of this site.

-Wes

[Chris'91'525i]

Hi all,

Anyone know what is the normal time between the compressor cycling on and off? I just got through fixing my AC (r12) system (no, I'm not crazy to do this in winter, I live in Hawaii ;) ), replacing a low pressure hose and expansion valve, along with the obligatory o-rings and drier.

Took it to a shop and had it evacuated and charged up, checked out ok with no leaks and I was on my way. Blowed ice cold, everything seemed fine, until I noticed as it was idling that I couldn't really hear the compressor going on and off like it's supposed to. I'm sure it should cycle every like 15-20 sec or something, and mine seems to just stay on.

If the pressure switch is screwed, will the compressor keep going until it completely overpressurizes the system, or is there a backup? I'm thinking I might have jacked up the pressure switch connections as I was trying to remove them - plastic over 18 years becomes a bit brittle, so parts of them kinda broke apart, but I thought I reconnected the wires ok. I dunno, do I need another switch?

Thanks for all your help, it's amazing how much I've done because of this site.

-Wes

You should be Okay, If you had a low charge it might cycle that fast, and the only way it would get "overpressurized" is if it was over charged with freon.
With the correct charge it will cycle based on evaporater temp. which will vary with ambient temp. inside and outside vehicle.
The compressor may stay on for awhile till inside Temp. stabilizes. and then start cycling the compressor to maintain thermostat setting.
There no set time for it to cycle, it's based on Temp., with the correct system charge.

[Wes F]

You should be Okay, If you had a low charge it might cycle that fast, and the only way it would get "overpressurized" is if it was over charged with freon.
With the correct charge it will cycle based on evaporater temp. which will vary with ambient temp. inside and outside vehicle.
The compressor may stay on for awhile till inside Temp. stabilizes. and then start cycling the compressor to maintain thermostat setting.
There no set time for it to cycle, it's based on Temp., with the correct system charge.

Thanks Chris, that makes me feel a lot better. I just didn't want to keep running it in fear that it wouldn't cut out and possibly do damage. What if I just wanted to check, does anyone know if there is a way to test the pressure switch to make sure it is functioning?

Thanks again.

[Wes F]

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