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'02 Olds Silhouette Loss of Cooling

Silent One on Fri September 07, 2007 10:55 PM User is offline

Year: 2002
Make: Olds
Model: Silhouette
Engine Size: 3.4L
Refrigerant Type: R134a
Ambient Temp: 83F
Pressure Low: 32
Pressure High: 70
Country of Origin: United States

'02 Olds Silhouette - began blowing hot air almost overnight. Suspected leak.

Ambient conditions:
air temp: 83F
humidity: 88%

Gauge readings as follows:
33 low side
100 high side
1500 RPM:
26 low side
102 high side
Vent temps: 83F

Compressor running continuously at both idle and 1500 rpm's. Compressor surging at idle with low side readings fluctuating between 35 and 29. Hissing sound from interior vents.

Added 11 oz virgin R134a out of a can. Compressor stopped surging. No more hiss from interior vents. Now for the strange part - gauge readings as follows:
48 low side
78 high side
1500 RPM:
38 low side
78 high side (basically no change)
Vent temps: 68F

The lower vent temps and higher low pressure readings seem to confirm low refrig charge but why are the high side pressures constant between IDLE and 1500 RPM before and after charge? Also, why did high side drop after charge?

Forgot to add that before charge the electric fan would be on low speed at 1500 rpms but after charge the fan would engage high speed at 1500 rpms as if the high side pressure side rose enough to trigger the high speed fan.

Edited: Fri September 07, 2007 at 11:00 PM by Silent One

Chick on Sat September 08, 2007 5:02 AM User is offlineView users profile

Your first set of pressures look normal, except for the low charge, but the second set of pressures don't look right??? maybe try connecting the manifold set again, making sure the 'wheels" are closed and also depressing the shrader valves... Look for your leak on the lower right side of the condenser, as that is where they usually leak iif it has the mitsubishi system. I have seen the leaks, but can't remember the two or three years they had that probvlem..But I think yours fall into that group.. If you see green dye on the condenser near the mounting bracket, thats it...Otherwise a UV dye test should find it, check all connections, front of the compressor etc...
Once you find and fix the leak, be sure to pull a deep vacuum and charge the system amount back into the vacuum..Hope this helps.

Email: Chick


Freedoms just another word for nothing left to lose

GM Tech on Sat September 08, 2007 9:29 AM User is offline

All '01-'02 olds silhouettes, chevy ventures, pontiac montanas,, buick rendevous, pontiac azteks are prone to condenser leaks- lower right hand corner (passenger side) just did one 2 nights ago--analyzed it without seeing it............

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......

Silent One on Sat September 08, 2007 3:12 PM User is offline

Thanks for the responses. I checked the condenser and it's dry as a bone. I put some uv dye in and will check with light in a couple of weeks. I put in an additional 7 oz of R134a and managed to get the low side pressures to 28 psi low and 110 psi high at 1500 rpm's and both low and high were steady as a rock. Vent temps were at 39F with blower on 3 of 5 so I would say that all indications are of a leak. I'll post back if I have any further issues. Thank you all again for your time assisting newbies like myself.

One more question - the sticker in the engine compartment says to use "synthetic" oil only in the a/c system - what specific oil type and viscosity does this vehicle use?

Edited: Sat September 08, 2007 at 3:14 PM by Silent One

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