Hi All,

I own a 2007 Ram 2500 with the 5.9 Cummins and I am having trouble with my climate control which I have not seen addressed in other posts. My unit blows cold air when at idle or driving slow but when I am on the freeway it stops blowing all together. When I slow down it comes back marginally until I shut it off and rest it awhile or hit a bump. Hitting a bump will cause the unit to blow again. I took out the blower and checked the blend door, it was intact and I cycled the blower thru all its speeds...........didn't see a problem there. I have read about a possible vacuum leak causing the mixing door to malfunction but I can find any information relevant to my truck year. Where can I find a vacuum diagram for this 2007 diesel truck and an engine diagram which shows the location of the vacuum pump. I believe the vacuum pump is above the AC compressor but I can not get a visual on it and would like to read up first on the removal. The hose on this truck which goes into the firewall on the passenger side is about 5/8 inch and larger than the others I have seen. Appreciate anyone's helpful comments.

Regards,
Dave Nolan

 

Is it possible that the evaporator core is freezing over with ice, blocking the airflow when you're at speed?...When it stops blowing, can you still hear the blower motor running?......Ben

 

The blower is still functioning and I can hear the speed change while turning the operating ****.

 

Then airflow is blocked, probably by ice...This can be caused by low refrigerant levels, or defective cycling switch......Ben

 

I've checked the drain hose and do not see any accumulation of condensation under the truck when I shut it off. My thoughts were possibly the wild vent theory?

 

You say stops blowing all together then hit a bump and it blows? The fan stops blowing air? Like it shuts off?

47

 

The fan continues to run its like the mixing or blend door changes position.