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Isn't the a/c compressor supposed to cycle on and off?

S

SimpleXJ

NAXJA Forum User
Location
east coast
Hi guys,

The a/c in my '89 hasn't worked since I bought it. That's been about 4-5 years. Today I decided to fix that and filled it with the "arctic freeze" from autozone, after installing the R134 conversion kit. I charged it to 35lbs on the low side. Don't have a way to test the high side. The compressor comes on, but it stays on. On my other jeeps (not renix) the compressor cycles on and off, this one just stays on. Is this normal? Is it going to blow up if I use it? If so, what controls the cycling? Where do I look? I haven't messed with the a/c electrical system except the stock e-fan wiring, which is just capped off because when I converted to an open cooling system, there was no where to put the sensor for the e-fan, which mounted in the old radiator. The only other thing I can think of that relates in any way to the A/C system is my heater controls - they are a bit worn. Defrost doesn't work unless I put the knob between defrost and heat. The rest of the settings work. When I put it on max, the compressor clutch clicks but never unlicks unless I turn off the a/c. All the wiring is factory except the stuff mentioned above.


Any help will be appreciated.

Thanks all

SimpleXJ
 
SimpleXJ said:
Hi guys,

The a/c in my '89 hasn't worked since I bought it. That's been about 4-5 years. Today I decided to fix that and filled it with the "arctic freeze" from autozone, after installing the R134 conversion kit. I charged it to 35lbs on the low side. Don't have a way to test the high side. The compressor comes on, but it stays on. On my other jeeps (not renix) the compressor cycles on and off, this one just stays on. Is this normal? Is it going to blow up if I use it? If so, what controls the cycling? Where do I look? I haven't messed with the a/c electrical system except the stock e-fan wiring, which is just capped off because when I converted to an open cooling system, there was no where to put the sensor for the e-fan, which mounted in the old radiator. The only other thing I can think of that relates in any way to the A/C system is my heater controls - they are a bit worn. Defrost doesn't work unless I put the knob between defrost and heat. The rest of the settings work. When I put it on max, the compressor clutch clicks but never unlicks unless I turn off the a/c. All the wiring is factory except the stuff mentioned above.


Any help will be appreciated.

Thanks all

SimpleXJ
Click to expand...
I dunno for sure but on max, my 1990's (when it worked) stayed on all the time also. If you can get a way to test pressures I would, but otherwise I wouldn't worry too much about it.
 
mine's an '88, and it also never cycles-- has not left me stranded.........yet-- but I have also only run the AC twice for longer than a minute to see if it would function. I checked pressures the first time I ran it and it was "functioning correctly" based on high and low side pressures. The second time I ran it for about 35min due to forgetting that I had turned it on to check the pressures the day before-- I had windows down and realized it was getting cold!

I guess until the high side get TOO high, it's gonna run!
--Shorty
 
Cool, thanks for clearing that up, guys. I have never messed with A/C on my renix jeep, and the 96 is chrysler mpi and that compressor cycles. When this one stayed on it kinda scared me.

Thanks for the help.

SimpleXJ
 
I know this thread's a little old but the compressor on my 99 stays on nearly constantly, and I would like to know why/ if there's a way to get the damn thing to cycle. I was wondering if maybe the charge is low, but not low enough to get it to do that "3-second-cycle" thing so it just works like crazy to cool? I put in 22 oz. of refrigerant, but I may have lost a considerable amount as my high-side fitting did not seat perfectly and was leaking at a loud hiss, I discovered after I had finished charging. But the AC was cold at this point, and is still cold.
 
When I filled mine, I got one of those cans where the hose has a crude guage on it. It works though, you can use the guage after the bottle is spent. I'd start with checking the pressure, make sure the system is fully charged. My 96 cyles on and off every 10-15 seconds or so.

Hope this helps

SimpleXJ
 
darjevon said:
I know this thread's a little old but the compressor on my 99 stays on nearly constantly, and I would like to know why/ if there's a way to get the damn thing to cycle. I was wondering if maybe the charge is low, but not low enough to get it to do that "3-second-cycle" thing so it just works like crazy to cool? I put in 22 oz. of refrigerant, but I may have lost a considerable amount as my high-side fitting did not seat perfectly and was leaking at a loud hiss, I discovered after I had finished charging. But the AC was cold at this point, and is still cold.
Click to expand...

If the charge is low, it will cycle too much. I believe the FSM for 99 states that anything over 10 cycles in one minute's time is considered too much, and a sign that the system is low on freon....I believe it's 10, i'll have to look that up again later.

On mine, it really all depends on how the outside conditions are as to how it's going to cycle. If it's real hot and mainly real humid, it will come on and stay on. However, if it's somewhat hot, and pretty dry, it will cycle on and off several times (but still well under the 10 times per minute rule).
 
I am a cross-posting whore (see JF and JU).

My 97 was cycling every 4-5 seconds as of spring '03. It was recharged, and since then it never seems to cycle. My XJ is a third car, and I rarely drive it when AC is needed (because I want the fragile, crappy 97+ system to last).

I ran it tonight, and had occasion to idle it for a few minutes when talking to a few people and it never cycled. This is in 80-ish degree temp and 90%+ humidity.

Thoughts?
 
My 92 xj runs all the time also. My 2000 had a leak and I found out if it is low it will cycle at an idle due to the low pressure cut off switch. If it's not low it will not cycle at an idle, BUT as the rpm's go up suction from the compressor brings the low side pressure down. If it goes below 25 it kicks of till the pressure comes back up above 25. You also have a high pressure cutout switch on the high side of the compressor.
 
TacticalFats said:
I am a cross-posting whore (see JF and JU).

My 97 was cycling every 4-5 seconds as of spring '03. It was recharged, and since then it never seems to cycle. My XJ is a third car, and I rarely drive it when AC is needed (because I want the fragile, crappy 97+ system to last).

I ran it tonight, and had occasion to idle it for a few minutes when talking to a few people and it never cycled. This is in 80-ish degree temp and 90%+ humidity.

Thoughts?
Click to expand...
Sounds normal to me. My 99 (now that I finally got it to hold some damn freon) hardly cycles when its hot and super humid. The hotter the humider it is, the less it will cycle. I run mine every day, as I do atleast 60 highway miles a day, and for once, haven't had any problems out of it this season (knock on wood).
 
Yes, it should cycle. The comp will stay on until the evap core git dow to 35 dagrees or such. When it over a hundred out side and you have the a/c on max and the blower on hi you have more air flow threw the evap, heating it up sp the comp is tying to get it cooled down, So if is hot outside is going to stay on. If a littlr cooler outside and you turn the blower down the comp should cycle on and off. Since you have converted it to r134 witch is less efficent then r12 the a/c system is working harder to cool the evap down so the comp may never cycle on and off so in the long run its not good for the comp. I had convered my 91 to r134 and on the highway it work okay but around town it sucked. This is because the condensor on the cherokee dont cut it for r134. It never got as cold as r12. So i went back to r12 and now its ice cold and it gets so cold i get ice on the ac lines. So in the long run stick with r12 thats just my opinion.
 
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