1991 Dodge Cavaran NO HEAT

I also noticed the AC unit cycles even though the AC is not on. It appears that the AC is over riding the heat. I disconnected the power to the compressor. Still no heat however but is not really cold now, kind of luke warm air.

gman1957 wrote:

Make sure that the blend air door is working. The door will seize and the cable will actually slide at the control making it seem like the door is moving but it is not. When you slide the temp control you should hear the door hit the stops. The water valve under the hood is used for A/C. it shuts the water off in the max cold position.

Glenn Beasley Chrysler Tech

Glen,

I checked the blend air door and it appears to be work> > I also noticed the AC unit cycles even though the AC is not on. It

Then I would suspect a stopped up heater core. Especially since you said it was hot going in and warm going out Glenn

clogged heater core?????

gman1957 wrote:

Great idea! I'll give you an update tomorrow.

philthy wrote:

I made some connectors and was able to flush the complete system. The heater core did spit out some gunk. I refilled the coolant, just water for now and I'm actually getting some heat. Not what I would expect, I'm not sue if when I drain some water and add anti freeze if that will change things.

The A/C will turn on if the panel is set to defrost. This is normal

Glenn

if the ac cylces while the defrost is on then it's working correctly it is suppose to remove moisture form the cabin and uses the ac to do so if it runs when the heat is on full heat then u have a issue

gman1957 wrote:

Some. It would be more useful if you put a thermometer on it and told us what you were getting from the duct. Water boils at a lower temp than coolant and cannot carry as much heat as a result.

Ted

There are some gains and some losses of pure water over water/entifreeze mix. Ignoring the boiling point, pure water will actually cool better (not sure if it's due to better conduction or higher specific heat capacity), but the lower boiling point is a minus of pure water if the temperature does get higher (but it may stay cooler due to the better cooling). The net overall effect would depend on the engine and conditions. Some people in racing actually try to eliminate or minimize the amount of antifreeze for this reason (also there are products like Water Wetter?). (Not arguing against using antifreeze - it prevents corrosion and lubricates the water pump - and as you say raise the boiling point.)

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

1995 Dodge Caravan here and am also experiencing the same problems as everybody else here and then some.

The heater does not seem to get hot anymore. It simply blows luke warm air if that.

I also have the problem of the air "magically" disappearing and coming out of the windshield vents. Even when it shifts over to that area, it hardly comes out.

When I get on the gas and the A/C is on the air stops coming out of the front vents and shifts up to the top vents on the dash too.

My concern now is getting the heater to work again. I have noticed that when I leave for work around 7AM it is about 36* outside and the heater NEVER gets warm. However, if I am driving home and it is in the 60-80* range the heater will spill out some heat, but not like it did in the past.

I am going to have my mech replace the thermostat and go from there.

Also, has anybody figured out how to fix the magic changing of the airflow?

gman1957 wrote:

The magic fix is to have the check valve at the brake booster replaced, the one that controls the little black vacuum hose. Your thermostat will more then likely fix your heater problem

Glenn Beasley Chrysler Tech