[blowe]

I have a 2001 Ram1500 SLT quad cab. Several things are going wrong @ 110,000 miles. First, the ac/heater will switch from dash to defroster under acceleration. I know this is a vaccum leak, but does any one know where to start?

#2, Have lost all but hi fan operation.

Any help would be greatly appreciated

 

[octaneman]

Hi blowe


Dodge has a very big problem with the ac\heater system, there is a door that mediates the flow of cold and hot air which may have broken off. To get access to it you will need to get to the a\c motor under the passenger side dash. This is not an easy task because the dash has to be completely removed along with the housing to fix it, whats worse it has the tendency to break if not handled correctly. Before you start tearing into the dash you will need to make a visual inspection of the condenser fan to see if its working. If the fan is not spinning with the a/c on, the problem could be limited there and replacing it may solve the issue. Should the condenser fan work then you will need to go under the passenger side dash.

post back your findings.

 

[octaneman]

Addendum:

For the blower motor ,on my first post I forgot to mention that the wires from the ignition switch to the blower may have burned. The problem is from within the switch contacts causing the fan to either be stuck on 1 speed or not work at all.

Note : Please have the ignition switch checked ASAP.

 

[kjms1]

blowe
As for the ac/heater switching doors on you ... all vehicles lose(drop) vacuum under acceleration
Most cars & trucks have a vacuum canister that stores vacuum so when you are accelerating you dont get a vacuum drop and the doors go to switching
look on the wheel well and see if you see a round plastic canister with 2 vacuum lines going to it one will go to the engine and the other will go thru the firewall and to the heater control switch .... if you cant see or hear a vacuum leak at the canister the prob is most likely at the heater swicth
now so had a one way valve spliced into the vacuum line thst would only let the vacuum go one way

 

[Raylo]

I had that exact same problem on my 1994 Camaro when it was brand new. The dealer said it was a pinched vac line in the dashboard and they had to totally pull the dash to repair. Sounds like Octaneman has you on the right diagnostic track but perhaps you could look in the engine compartment at the vac line(s) that go through the firewall to supply the HVAC system to see if any are pinched or broken. Probably a long shot, tho....

 

[kjms1]

little baffled how can a heater door broke or not moving have any kind of effect on the rad fans

blowe
need you to explain the rad fan operation does the high fan come on with the ac off as the truck heats up or does the fan only come on with the AC on

 

[Thebigm9000]

I ended up having to replace the whole system, I had the same problem with the a/c switching to defroster under acceleration, its a big problem. i just replaced it and havent had a problem since.