Heat comes out defroster instead of panel when going up hills, because....

Old 11-26-05, 03:25 PM
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Heat comes out defroster instead of panel when going up hills, because....

...obviously the engine vacuums drops, due to me pushing down more on the gas pedal. But where do I start looking? I am pretty savvy with car repairs, just so we get that out of the way. But this problem is one of those spaghetti nightmares probably, with vacuum lines here and there under the hood, under the dash, etc.

This is for one of those '91 Dodge Spirits with the very common, many made/many still on the road) 2.5 liter 4 cylinder engines. The problem is slowly getting worse. Now it shifts from panel heat to defrost when I go up lesser incline hills.

Then I have another problem that suddenly developed: When the transmission shifts between 1st and 2nd gear, or from 2nd to 3rd, it slips like clutches are slipping. The engine suddenly revs up between shifts. But here is the odd part: Once the shift is completed, within like 1 second of slipping, it is a good positive lockup. So, for now, I am manually shifting. Could I really be so lucky that something is out of adjustment like I read about? Any one here have or know of that problem?

Last edited by ecman1; 11-26-05 at 07:37 PM.
Old 11-27-05, 06:29 AM
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First the HVAC problem. There is a vacuum leak. Look at the brake booster. There should be a check valve with a vacuum hose on it that runs through the firewall. That check valve will cause that problem. Very inexpensive part. Also, if that doesn't take care of it, check under the dash for cut/kinked vacuum hoses to the door actuators. If none, the heater control head is faulty.
Second. the trans. Check the linkage under the battery tray. When the kickdown lever rusts, it will cause all sorts of shift problems. Look at the lever with the spring attached. That lever should move back and forth freely. If not, spray rust penetrant and work it back and forth until it does.

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