Heater

[sunoco nut]

I hope someone can help me!my heater comes on whenever i accelerate or put a load on the engine.i am leaning twoards a vacuum problem but i would appreciate any advise.this even happens when the a/c is on.

[mike2004tct]

Originally Posted by sunoco nut

I hope someone can help me!my heater comes on whenever i accelerate or put a load on the engine.i am leaning twoards a vacuum problem but i would appreciate any advise.this even happens when the a/c is on.

Not much help, but it sure sounds like a vacuum problem, or a failure in the blend door motor assembly. Find the blend door and you may find your problem.Any work behind the dash can be painfull.
Good Luck

[TEXAS-HOTROD]

The one time I used my heater (not many cold days here), the thing stayed on full hot. Come to find out the control rod popped off the flap arm. That's a different issue anyway.

Does the heater actually blow hot? Or does the air die die down?
There should be a one-way check valve in the vacuum supply line that goes to the intake. check the vacuum can and see if any hoses are cracked.
It sounds like vacuum loss to me.