Heating issues

[Pappy206]

Hello, I've got a 1994 grand caravan with a 3.8L engine. I can't get heat in the thing.

I've replaced the thermostat with a good one. We went through few at a friends shop to find a good one. I've flushed the heater core and the radiator separately and together... This has been done in a service garage as well. The flow seems fine when doing that.

Still no luck. As it stands, if I squeeze the hoses going into the heater core (like milking a cow) I can get heat for a few minutes if I keep the rpms up. Fought the thing from Nevada to Ohio and survived..lol. However, I'd still like to solve this problem.

The system seems to be holding pressure ok when I open the radiator.

Any ideas?

Thanks in advance for any help!
- Pappy

[tempfixit]

Here is a link for free online service manual, it may also be available at your local library.

http://www.oplin.org/databases/proxy...%2fframerq.asp

enter 123456789 for library card number submit
click on the box with a library in it and more will appear, click on the Public Library of Cincinnati and submit
scroll down to Auto Repair Reference Center ARRC submit
choose year, make, model and engine

Go to TSB's and Recall's and scroll down to Heater and AC system tsb, choose the Poor Heater Performance TSB 24-03-94.

Does your heat lever on the control panel bounce back 1/8th inch when moved from cold setting to hotest setting?
TSB 24-03-94 has a procedure to readjust cable for blend door.

Good Luck

[Pappy206]

Thanks for the reply and info! No, the controls seem to be working fine. No binding or springing back.

In some ways it seem like a vapor lock type event. Though I'm just a backyard mechanic at best.

[tempfixit]

The heat control lever is suppose to back when moved to the right compltely, like 2mm I believe, check out that TSB in the post earlier. It is easy to do takes maybe ten minutes at tops.

I also had a problem on a 95 with 3.3 not heating the way it should, replaced thermostat and didn't help. I am thinking that I also had air in the system so yesterday I removed the hoses off the heater core and did a core flush using water with a garden hose. Get your self a barbed 5/8" hose to garden hose fitting and use a short piece of hose to connect the coupled hose to the heater core along with a piece of hose 4 to 5 feet long so it hangs over the grill and bumper so you don't get the engne wet. I flushed it both directions.
I also gave it a blast of compressed air.

If you can raise the front of vehicle up, either on a steep grade or car ramps usually helps. It took quit some time to get the air out of system leaving the radiator cap off and heater control switch to full heat fan speed on high, but it gives off good heat now.

It seemed to relieve the air in system most when the radiator fans switched on and thermostat open.

Good Luck

[Pappy206]

The routine you used for flushing sounds like the same thing I've been doing basically. Done that twice as well as flushed the entire system once. The flow has been good each time.

However I might try to get the air out of the system here as well. It does put out some heat after milking the hoses (like I described earlier). So perhaps if I try that with the radiator cap off I may be able to bleed the air out. Don't have much to lose by trying and it's a decent day outside so I may as well get into something.

I did read the cable issue and will give that a whirl too.

Thanks again for the ideas!