<FONT face="Times New Roman, Times, serif">I HAVE A 2000 RAM VAN 2500 I HAD THE HEATER RESISTOR FIXED AND A VACCUM POT REPLACED (A ROUND THING WITH A VAC LINE INTO IT) BUT STILL HAVE A PROBLEM. WHEN I ACCELERATE WITH THE HEAT ON THE HEAT CHANGES TO DEFROST THEN WHEN I LET OFF IT CHAGES BACK TO HEAT.THE 5 STAR DODGE DEALER HAS HAD THE VAN IN 3 TIMES FOR THIS NO FIX YET...ANY TAKERS..THANK MIKE POLETTI</FONT> <edited><editID>m38mpp</editID><editDate>37993.6712037037</editDate></edited>

 

Hello are you having problems with the windows fog up?</P>


</P>

 

NO THE WINDOWS DO'T FOG BUT LIKE I SAID THE AIR SWITCHES FROM COMING OUT THE FLOOR TO THE DEFROSTER AND WHEN I LET OFF THE GAS IT GOES BACK TO NORMAL

 

Sounds similar to a prob I had on an old Ford.</P>


Here we go...</P>


Most climate control systems are vacuum operated. The system gets its vacuum from the engine.</P>


What happens is when you step on the gas, the engine creates more vacuum. </P>


Sooo.. its possible that with more vacuum it will collapse a vacuum hose to your climate control, (they are about 3/16 in diameter).</P>


What causes it to open and close under acceleration is the air diffuser inside your plenum is spring loaded with a vacuum diaphram. If the vacuum hose is collapsed, the diaphram is released and the spring pulls the diffuser to defrost.</P>


I hope this helps. Dont know if it applies in your case but should give you some insight.</P>


If I am wrong I hope someone will correct me.</P>


</P>


Jeff</P>

 

m38- does it have air conditioning????

 

looking at the manual- check for 8" of vac, check the vac check valve- if it cann't keep the vac on the one setting- the low rpm's may cause the actator to change due to low vac source.</P>


check for a cracked, broken or loose vac on engine, check valve, reservoir and control unit.</P>


</P>


john</P>

 

BROUGHT IT BACK TODAY AND THEY FINALLY FIXED IT TOOK THEM TWO HOURS TO FIND IT.IT WAS AS YOU SAY A CHECK VALVE NOT HOLDING THE VAC UPON ACCELERATION. THANK YOU FOR YOUR HELP I GAVE THE DEALER A HEADS UP ABOUT THIS FORUM AND THATS PROBABLY WHAT HELPED HIM FIND IT. THANK YOU,MIKE P</P>

 

10-4 HAPPY HEATING!!!!!!