Dash HVAC controls not working

RLS7201 wrote:
First off you need to know who the manufacture of you AC system is.
Evens Tempcon is pneumatic control.
Denso is all electrical control.

Richard

After over a year of just "dealing with it," I stumbled across this gem today. I popped the front access cover, looked inside and started checking the lines. I heard a slight hiss when messing with the vacuum supply line off the electric vacuum pump at the bottom of the ball, popped a zip tie to give me more working line and shoved it farther on the nipple... And my A/C is perfect again!

Yes, I said vacuum pump. I have a 95 Safari Continental DP. The HVAC is vacuum controlled, and all the vacuum runs off an electric pump bolted to a cross member in front of the engine (under my bed). All you diesel guys don't discount the advice.

Next piece, my controller *should* be Delco/Remy. I swear I have seen the same panel in old Chevy trucks (odd push-button selector for modes, fan lever on the right side). Anyway, it is obviously vacuum-controlled.

Thanks for the great forum and the information!

IF your rig is a GASSER then the doors or gates that direct the air flow are most likely operated by vacuum motors, you have lost vacuum or the vacuum connector has come off the selector switch.. I have seen both.

LOSS of vacuum can be because of a broken hose, a leak in the brake booster (if you have a vacuum booster) or cruise control servo (if you have one of those and it is vacuum operated).

Again, I've seen all the above on older cars.

Thanks to all your help, this was a very easy fix.The vacuum hose going to the vacuum ball was loose.After securing it, everything worked as designed. Thanks again! Bill

Does sound like loss of vacuum.

Troubleshooting for Evans Tempcon; Evans Tempcon
1. At the bottom of the page "click for tech support"
2.Then agree to the "disclaimer" page
3.And on the next page---When you select HVAC troubleshooting, it will show the various models and each has very through troubleshooting.

A little involved but usually well worth it....Hope it helps.

First off you need to know who the manufacture of you AC system is.
Evens Tempcon is pneumatic control.
Denso is all electrical control.

Richard

Yes, vacuum controls are common and defrost is the default position if no vacuum present. Start at the engine intake manifold and trace the vacuum line to the dash HVAC controls. Yes, it could also be a defective vacuum motor allowing vacuum to escape, but checking the vacuum lines is easier and a good bet.

My '07 F350 did that 4 times. Each time it was due to rats/squirrels/??? chewing vacuum hoses and wires under the hood.

Not sure how many HVAC controls are vacuum controlled anymore. GM vehicles, for example, are notorious for the actuator motors to fail, causing the problem you describe