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When AC is on Compressor clutch does not cycle


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tractorboy
User
tractorboy profile image

May 31, 2022, 9:12 AM

Post #1 of 5 (196 views)
When AC is on Compressor clutch does not cycle Sign In

2002 Nissan sentra 1.8L
1. the compressor clutch engages when the AC is turned on
2. produces really cold air
3. I replaced the low side hose from compressor to evap. was leaking
4. pulled a vacuum on the system
5. filled with the correct amount of 134A refrigerant using a scale.
6. after driving for 20 minutes the coolant temp will spike.
7. w/o the AC ON the coolant temp is slightly below halfway.
8. I checked the coolant protected to 265°.
9. compressor clutch never cycles, stays on constantly with the AC on
10. the low side is within Nissan's specs at 31psi high side is at 150psi which is about 30 psi lower than the min for Nissan's specs 86° ambient temp.
11. both fans are turning.
12 I assume that on the freeway going 70mph the fans have little to do with cooling? still will spike at this speed too with the AC ON


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

May 31, 2022, 9:52 AM

Post #2 of 5 (185 views)
Re: When AC is on Compressor clutch does not cycle Sign In

OK, so what is the problem? It's not supposed to cycle unless it freezes up.

Fan operation is determined by pressures and many are wired to run all the time with AC on.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



tractorboy
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May 31, 2022, 2:00 PM

Post #3 of 5 (170 views)
Re: When AC is on Compressor clutch does not cycle Sign In

well HT that does not seem to be the consensus on the net about the clutch cycling. seems to be around 15-20 minutes , 1 cycle , i would assume a duty cycle of 50/50 , i don't know could be a duty cycle of 70 /30 . in the Nissan manual i have it says compare the clutch cycle with the chart....no chart. i just do not know , never saw the freezing up. freezing up wouldn't that be air in the system? yeah i have read that about the fans that they come on as soon as you turn the A/C on. i was just stating that as a fact because what is happening is that the car is overheating with the AC is on.on surface streets and highway. with the clutch always on wondering if it was putting a load on the motor. so how does the AC know when it has reached the cabin temp? there is an ambient temp sensor i think that is on the outside somewher. do you have access to all data could u look up the high low side psi for 85°


(This post was edited by tractorboy on May 31, 2022, 2:04 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

May 31, 2022, 2:09 PM

Post #4 of 5 (162 views)
Re: When AC is on Compressor clutch does not cycle Sign In

This thread isn't going to go very far if you're going to argue with me about what I know to be fact.

I'm only going to explain this once.

There are very different operating systems and they work very differently. What you are describing is a CCOT system that does cycle according to pressure. That system uses an orifice tube and an accumulator.

Your car uses an expansion valve and a dryer which does not have a cycling switch and does not cycle. It uses a thermostat in the evaporator which shuts the compressor down only when the evaporator starts to freeze. Other than that it runs all the time.

Now if you choose to listen to Dr. Google instead, I'll be happy to close this.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



(This post was edited by Hammer Time on May 31, 2022, 2:10 PM)


Nacho
User

May 31, 2022, 8:06 PM

Post #5 of 5 (140 views)
Re: When AC is on Compressor clutch does not cycle Sign In

Your Sentra's A/C cycles on and off by means of a thermostat (evaporator temperature control) inserted in the evaporator. Engine oveheating may be caused by several factors, like a faulty water pump, a faulty engine thermostat, or even a clogged catalytic converter. If your compressor doesn't cycle on and off, I'd check the thermostat first. In the 02 Sentra is below the center of the dashboard, behind a blac plastic cover. If you need more info and diagrams, let me know. ]
You'll teach them to fly, but they won't fly your flight; you'll teach them to dream, but they won't dream your dreams; you'll teach them to live, but they won't live your life; however, in every flight, in every dream, in every life there always be the print of your lessons taught (Mother Theresa)






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