Automotive Air Conditioning Information Forum (Archives)

rameam on Mon June 11, 2012 5:48 PM

Year: 2003
Make: Pontiac
Model: Montana
Engine Size: 3.4
Refrigerant Type: R134?
Ambient Temp: 93
Pressure Low: 25
Pressure High: 110
Country of Origin: United States

AC not blowing cold. Pressures seem to be OK, but high side line not hot, suction line not cold (don't understand why when pressures seem to be fine). Fans, relays, fuses are all fine. I have come to a conclusion that the underdash door that switches from heat to AC may not be closing properly on AC (???). Any other ideas?

GM Tech on Mon June 11, 2012 6:03 PM

Low side line would be cold if temp door was an issue - your main concern is the line is not cold---

65% of mobile a/c failures are due to loss of refrigerant due to a leak---so you probably have a rear air evap unit-- the lines underneath are notorious for leaks under the rubber insulation-- look for green dye emitting along any of the a/c lines-- the dye was installed at the factory......find and fix your leak evac and recharge to spec...

Have refrigerant recovered and weighed to prove if you are low on charge or not.....

-------------------------
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......

GM Tech on Mon June 11, 2012 6:03 PM

Low side line would be cold if temp door was an issue - your main concern is the line is not cold---

65% of mobile a/c failures are due to loss of refrigerant due to a leak---so you probably have a rear air evap unit-- the lines underneath are notorious for leaks under the rubber insulation-- look for green dye emitting along any of the a/c lines-- the dye was installed at the factory......find and fix your leak evac and recharge to spec...

Have refrigerant recovered and weighed to prove if you are low on charge or not.....

-------------------------
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......