AC assistance - ofcourse its hot in NE today

Joined
Apr 7, 2004
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Location
Reno, NV
My AC has been working fine recently, although not COLD air, but cool enough for the 80 degree temps lately. Today, I take off and turn on the A/C and I have nothing but warm air, this is a dramatic difference in temp from the cool air I got just yesterday. I turn the A/C on and off a few times and realize I dont hear the compressor turning on or changing the idle of the truck.

So here I am with FSM in hand, I have checked the tension in the belt to the compressor and its seems fine. Next thing to check seems to be the magnetic clutch .... what is this? I cant find it in the diagrams in the FSM? It's also saying I should be checking for abnormal noise .... what would this sound like? I know next to nothing about the A/C system, but am assuming the compressor pulley should be spinning all the time and this magnetic clutch would engage when I hit the button in the cab and the idle would change and I should have AC. Are there any easy and obvious things to check before I start really digging into it? Any help is greatly appreciated ..... THANKS!!
 
Joined
Feb 7, 2005
Messages
141
Well like you I'm not an AC expert, but while in park and the AC off you should see the idle at about 650 rpm, when you press the AC button you should see (idle) about 800 rpm; at this point the clutch should engage.

BTW with the hood open I really can't discern a noticeable increase in audible AC emissions.
 

flintknapper

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May 22, 2004
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Montana Cruiser said:
My AC has been working fine recently, although not COLD air, but cool enough for the 80 degree temps lately. Today, I take off and turn on the A/C and I have nothing but warm air, this is a dramatic difference in temp from the cool air I got just yesterday. I turn the A/C on and off a few times and realize I dont hear the compressor turning on or changing the idle of the truck.

So here I am with FSM in hand, I have checked the tension in the belt to the compressor and its seems fine. Next thing to check seems to be the magnetic clutch .... what is this? I cant find it in the diagrams in the FSM? It's also saying I should be checking for abnormal noise .... what would this sound like? I know next to nothing about the A/C system, but am assuming the compressor pulley should be spinning all the time and this magnetic clutch would engage when I hit the button in the cab and the idle would change and I should have AC. Are there any easy and obvious things to check before I start really digging into it? Any help is greatly appreciated ..... THANKS!!


Not trying to put you off....but do a "search" here, we have had alot of A/C discussion in the past month. Just about everything has been covered.

Good luck, and post again if you don't find an answer.
 
Joined
Apr 7, 2004
Messages
1,235
Location
Reno, NV
flintknapper said:
Not trying to put you off....but do a "search" here, we have had alot of A/C discussion in the past month. Just about everything has been covered.

Good luck, and post again if you don't find an answer.
I hear ya, but I did search today, just have not found anwsers to the questions in the FSM, most everything had dealt with the amount of freon/R134 in the system and such.

I'm wondering what the FSM descirbes as "abnormal sounds" sounds like? I dont think this has anything to do with the cooling agent but with the hardware.

Again, some of this may seem obvious others, but its greek to me looking at the FSM and I AM trying to shake this out myself.
 
Joined
Jun 16, 2003
Messages
1,805
First to answer your question, the clutch is part of the compressor pulley assembly.

From your description "although not COLD air" your AC has not been working properly for a while. If it were working properly the air would indeed be cold. Likely candidate problems are clogged system or refrigerant leakage resulting in low pressure. If the refrigerant charge is too low the clutch will not engage. This design is to protect the compressor from seizing when the system is low on oil. It is likely further diagnosis is going to require the use of pressure gauges to monitor the system while in operation.

I'd suggest you find a text on automotive AC repair and plan on investing in some diagnostic equipment – a couple of thermometers and a set of pressure gauges. Otherwise just take it to an AC shop. Most likely they can diagnose the problem in a few minutes.
 
Joined
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Messages
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Location
Reno, NV
Rich said:
First to answer your question, the clutch is part of the compressor pulley assembly.

From your description "although not COLD air" your AC has not been working properly for a while. If it were working properly the air would indeed be cold. Likely candidate problems are clogged system or refrigerant leakage resulting in low pressure. If the refrigerant charge is too low the clutch will not engage. This design is to protect the compressor from seizing when the system is low on oil. It is likely further diagnosis is going to require the use of pressure gauges to monitor the system while in operation.

I'd suggest you find a text on automotive AC repair and plan on investing in some diagnostic equipment – a couple of thermometers and a set of pressure gauges. Otherwise just take it to an AC shop. Most likely they can diagnose the problem in a few minutes.
Thanks Rich! I did not know a low refrigerant level could keep the compressor from engaging, so that helps a ton. There is a bunch of information on here about using proper gauges etc to test for system pressure, so I can start there.

:cheers:
 
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