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97 monte carlo no ac clutch engagement

partsguy on Wed June 04, 2008 7:20 AM User is offline

Year: 97
Make: chevrolet
Model: monte carlo
Engine Size: 3.1
Refrigerant Type: r134a
Ambient Temp: ?
Pressure Low: ?
Pressure High: ?
Country of Origin: United States

I am working with a 97 chevrolet monte carlo the ac clutch is not engaging, I have changed the pressure switch at the receiver drier ,checked all the connections and still cannot get the clutch to engage. I was checking out the ac diode located in line, does anyone know if these are prone for failure? I would really like to get this unit working. oh also the system is not overcharged, checked that as well.

Chick on Wed June 04, 2008 7:46 AM User is offlineView users profile

What are the system pressures, static pressure if thats all you have. Is 12v getting to one side of the cycling switch? Is it leaving the switch? Does it have auto temp conttrol, or manual.

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

GM Tech on Wed June 04, 2008 8:54 AM User is offline

Sorry chick- no cycling switch on this V-5 system- it has a pressure transducer- that needs to see 47 psi to engage the clutch-- so most likely he has lost charge- due to a leak (Shaft seal) - these W cars are all alike-- the 3.1L engine is the clue- they all use the V-5 compressor- from early 90's on up.....I'll bet he has about 10 psi in it........

Just remember- 65% of all a/c failures (at least in my massive database) are due to loss of refrigerant-- so play the odds......

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

partsguy on Wed June 04, 2008 9:40 AM User is offline

according to the cheap pressure hose with the gauge on it the system shows to be in the 50 or yellow state which shows an overcharge the car is about 100 miles from here.

NickD on Wed June 04, 2008 9:50 AM User is offline

I love my battery eliminator power supply for quickly checking the pull in voltage of the clutch, showing the current draw, and letting it cook for five to ten minutes to make sure as the coil heats the current decreases like it should. But a cheap DVM with a ten ampere current range will do with a jumper lead, connect the jumper to the ground side of the clutch coil to the neg bat term and the meter on the ten amp range from the positive side of the battery to the hot terminal, can read the current and the clutch hub should give a positive click sound. The rest is checking for voltage drops between the hot side to the source with the vehicle connector inserted and the AC on with the ignition in the run position. That diode is a flyback diode and even cheap meters have a diode check, low resistance in one direction, high in the other.

But the clutch won't work if you don't have correct operating pressures, need gauges for this. Find AC work amusing in that you can buy the starter kit listed in this site with a complete payback for what it would cost for one trip to the shop, then you have this equipment for future use. But without the test equipment, even the best of us would be dead lost and the worse possible thing to do is to guess.

GM Tech on Wed June 04, 2008 9:57 AM User is offline

That gage has colored "zones" that only mean something when the compressor is turning-- otherwise this is the static pressure which needs toi be 47 psi to engage the clutch-

I assume your 50 psi is static pressure-- which if it is 70-80 deg outside means you should have about 70 psi in a fully charged system- if your ambient is 70-80 and you have 50 osi static- you have about 4 ounces in a 2 lb system- an extreme loss of refrigerant--

The 50 psi on a cheap gage could actually be 45 or 55 psi due to cheapo gage error-- so you are real close to engaging the compressor-

What is your ambient temp???


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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

mk378 on Wed June 04, 2008 10:29 AM User is offline

Yes that system is almost empty that's why it doesn't engage. Knowing the ambient temp you can look on a pressure-temperature chart (or a regular gauge that has a temperature scale) and find the corresponding vapor pressure. The static pressure should be equal to that if the system contains at least some liquid refrigerant. If it is less that means there is only a little gas left, not nearly enough to get cooling.

Also charging by pressure with a single gauge is not going to work a variable compressor system.

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