2000 Montana Rear A\C warm but front is cold

[truc0011]

The air conditioning in the front vents comes out cold, but in the rear vents it comes out warm. Any ideas? I'm thinking the charge is slightly low. Has anybody encountered this?

[LMP]

I'm not sure with the 2000, but in previous years, heat to the rear heater core was controlled by a coolant valve in the engine compartment that closes when VENT or AC is chosen. IN mine, the valve vacuum actuator actually separated so the valve would never change position other than the last one it occupied before the failure...so it would be possible the cooled air is heated again ....
Of course, I also suppose your Montana actually has both the front and rear A/C. MIne has front A/C, but only heater in the rear.

[truc0011]

Originally Posted by LMP

I'm not sure with the 2000, but in previous years, heat to the rear heater core was controlled by a coolant valve in the engine compartment that closes when VENT or AC is chosen. IN mine, the valve vacuum actuator actually separated so the valve would never change position other than the last one it occupied before the failure...so it would be possible the cooled air is heated again ....
Of course, I also suppose your Montana actually has both the front and rear A/C. MIne has front A/C, but only heater in the rear.

What year is yours? Where is this valve located?

[Lanner]

Funny but I'm having the opposite problem. I have warm air coming out of the front and cold air coming out of the rear. So I'm hoping its nothing major (like condensor). Anybody have any help? ...Might there be some type of switch problem???? we can look into.

[truc0011]

Originally Posted by Lanner

Funny but I'm having the opposite problem. I have warm air coming out of the front and cold air coming out of the rear. So I'm hoping its nothing major (like condensor). Anybody have any help? ...Might there be some type of switch problem???? we can look into.

It wouldn't be the condensor if there is any type of cold air coming out. Typically when the condensor goes bad (leaks) all the freon leaks out and no cold air comes out of anywhere. I just replaced the condensor in my 1999 Pontiac GTP its not a bad job if you have all the right tools....i.e. vaccum pump to evauate the system and all the a\c hoses to charge the system.

[LMP]

Originally Posted by truc0011

What year is yours? Where is this valve located?

'93...same setup from 90 to 96. Valve was hidden low along firewall, near right wheel well..extremely hard to reach..in fact I just forgot about it: you just make me think I should insist and pay a visit .....
this http://www.autolib.diakom.ru/CAR/Pon...RAMS/19922.pdf is from '97..look at bottom right of schematic. It seems it is rather an actual electric motor used to position a diverter flap like the front heater...and this device is quite often the source of incorrect temperature setting for the front too....here is the looks of the front one: probably the rear is similar... www.avigex.ca/xport/actuator.jpg
...and yes, I checked at www.rockauto.com and the actuator is the same for front and rear.

[JTZ2000]

2000 Montana with rear A/C-Heat. I am having the same issue. A/C blows very cold up front. Regardless of if the front or rear knob is controlling the rear temperature, the rear air temp never cools down. I removed the rear-driver side access panel to get at the rear A/C-Heat module. I set all knobs on COLD/ HI FAN, and noted that the rear evaporator does not get cold.

Gives credit to the fact that there seems to be a valve up front not allowing the rear to cool. Will keep you posted as I learn more. Thanks.

[JTZ2000]

OK, I took apart some of the rear ducting and got to where I could see all the components: Blower Fan, Rear Vacuum Valve actuator, Rear Electric Temperature Door Actuator(mentioned by LMP), Rear Heater core, and Rear evaporator.
I could physically see the Electric Temp door cycling correctly. To get at the rear electic motor you have to take two top bolts and the lower nut off of the Module, tip it inward and you can see the electric servo at the top with two black and one brown wires. And since the ducting was removed, I could see into the flap and even see and reach the evaporator.
I also took the trim pieces off of the center console and under the stearing wheel. At about knee level you can look up and see the Front temperature door electric servo. I can cycle the front temperature control and physically see the electric motor turning correctly. So, both of my temperature control "valves" appear to be operating correctly.
Some things I noted at the rear: 1.)One of the lines into/out of the Evaporator does get cool to the touch...although not as cold as the one in the engine compartment, 2) I can reach in through the ducting and touch the evaporator fins. They are not cold...Should they be? 3.) The heater core is hot, I mean really hot. 4.) Disconnecting the vacuum hose at the rear vacuum actuator reveals no vacuum at the line??? I can physically turn this valve though and it makes no difference in the coolness of the air.

Why am I not getting cold A/C out of the rear vents???
2000 Montana, Front and Rear A/C

[mrobie]

Hi,

I just had this fixed in my Montana 1999.

There is a rear thermal expansion valve that needs to be replaced.
The AC refrigerant must be evacuated, then the valve replaced, then the AC recharged.

The part can be purchased for about $50.00 at NAPA
http://www.napaonline.com/masterpage...xpansion+Valve
NAPA Part number: TEM217110

Mike

[JTZ2000]

Yes, that fixed it for me too! Thanks for the help.
Jake

Originally Posted by mrobie

Hi,

I just had this fixed in my Montana 1999.

There is a rear thermal expansion valve that needs to be replaced.
The AC refrigerant must be evacuated, then the valve replaced, then the AC recharged.

The part can be purchased for about $50.00 at NAPA
http://www.napaonline.com/masterpage...xpansion+Valve
NAPA Part number: TEM217110

Mike