A.c. clutch

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Ian_Olivas

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So this isn't for my truck but ac systems are all similar. On my 2001 Nissan frontier the ac clutch is engaging and disengaging but long enough for the ac to cool. What would be causing this to happen? The compressor works because when the clutch does decide to engage it gets cold as hell, both lines were replaced a year ago and the high and low valve was also replaced a year ago, I checked the pressure and it was at 45psi right in the middle of the green.
 

crash68

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If the low side pressure isn't dropping much below 45psi before the compressor cuts out, It could be a high pressure control or possibly a temperature sensor that's causing it. Is there a cooling fan(radiator) that runs while the AC is on?
 
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Ian_Olivas

Ian_Olivas

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If the low side pressure isn't dropping much below 45psi before the compressor cuts out, It could be a high pressure control or possibly a temperature sensor that's causing it. Is there a cooling fan(radiator) that runs while the AC is on?
On this truck no that was first guess then I popped the hood and didn't see one. My friends brother works in a shop and he said if the lines were changed the orifice tube was also changed out and it's not a leak cause it's been doing this for over a year and the pressure is good. My guess is it could be the drier clogged or the high/low pressure switch is bad. I'm in the middle of vacuuming the freon out and I'm going to change them just want some more input on what it could be. After this I'm only left with the ac condenser or the evaporator core and I doubt it's that and I hope it's not cause I don't wanna pull the dash lol
 

crash68

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Since the refrigerant is coming out, change the pressure switch(es), filter drier and orfice tube. Orfice tubes are cheap and usually not too difficult to change, I've see a few plug up.
 

yoda

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whats your high side pressure before the compressor kicks off?
 
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Ian_Olivas

Ian_Olivas

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whats your high side pressure before the compressor kicks off?

Not sure. Why? And how would I find this out? I just changed the drier and pressure switch. I'm going to fill it up in the morning and hope it works properly
 

yoda

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The high and low pressure readings would tell me a lot more what is going on.
You would need a set of gauges to find this out.
 

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Not sure. Why? And how would I find this out? I just changed the drier and pressure switch. I'm going to fill it up in the morning and hope it works properly

You can't just "fill it up". After you open a system for service such as changing the drier you MUST evacuate it with a vacuum pump. After you evacuate the system it should be weight charged. You can easily destroy your compressor by not removing the air first. Also you would get your high side pressure by using a proper manifold set.
 

justin13703

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Yeah you definitely need to get high and low pressure readings to start with. If the pressure is out of whack either way it will cause the compressor to cycle like that.
 
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Ian_Olivas

Ian_Olivas

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You can't just "fill it up". After you open a system for service such as changing the drier you MUST evacuate it with a vacuum pump. After you evacuate the system it should be weight charged. You can easily destroy your compressor by not removing the air first. Also you would get your high side pressure by using a proper manifold set.


My friend had the vacuum that we used to discharge the system and vacuum it before we filled it back up with the freon. So don't worry there was no air in the system. The truck called for 1.43 lbs +- 11lbs so we filled it exact. His boss hooked up a set of gauges to it and didn't say anything was wrong, so either he didn't know how to read it or my friend was right when he said his boss sucks at diagnosing. But the new drier and pressure switch is installed with the proper amount of freon in the system. The the ac clutch was doing the same thing. Just flipping on and off when it felt like it but then later that day it was working fine like perfect and the ac was ice cold but then today it was like ehh. So new they came to the conclusion it most Lilly the module in the compressor that's going bad and not engaging the clutch or the expansion valve going to the evap core but his boss isn't even sure if it has an expansion valve in this vehicle and I swear his boss is the worst kind of mechanic sometimes but he does know his **** on everything else when it's not the ac lol. What are y'alls opinions? And if you really need those reading from the high and low side I will try to stop by the shop again and see if he can hook up the gauges and tell you what they read
 

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