Heat

[CRM1988]

As far as i can tell the vacum system is working but getting cold air in with the heat????Any ideas?

[TrailReadyMJ]

The flapper for the hot/cold is mechanical, operated by a cable, so make sure it's functioning properly first.

If it's a closed cooling system (Renix) you could have air trapped in the system. You can try burping it to see if it helps (did on mine!!!).

 

If you don't know how to properly burp a closed cooling system, here ya go...

 

1) Park on a hill, facing downhill. It has to be steep enough that the back od the engine is higher than the front.

2) LET IT COOL DOWN! Then locate the coolant temp sensor on the back of the head. This sensor will have one wire attached (brown IIRC), and threads into the top of the head toward the drivers side.

3) Top off the tank/pressure bottle and keep cap loose. You will want to be able to tighten it down quick though, read below.

4) SLOWLY Remove the sensor from the head using a 1/2" socket. An extension and swivel can be handy here too. Be very careful to not lose the sensor, and keep it ready to put back in real quick!

5) Once coolant flows from the sensor location, re-install the sensor. (this will/should only take a second!)

NOTE: the sensor can sometimes be tricky to get started, especially when plugging a hole where coolant is flowing out. You can slow the flow of coolant by tightening the pressure cap, just make sure it doesn't stop and suck air back in before the sensor is tightened down.

Make sure your pressure tank remains full at all times! The last thing you want to do is suck air back in. Think of it like bleeding brakes.

 

If all of that is ok, it could be the coolant valve or at worst a clogged heater core.

[sinkrun]

You may want to flush the heater core also it helped mine allot. Take both hoses off the firewall inlets take your garden hose and run water thru both ways it should push some brown crappy water out. Go both ways and give it a couple minutes.

[juan]

Flushing the core got rid of a lot of nasty color fluid and restored my heat - give it a try is quick and easy.

[October_V]

Just a thought, my temp selector switch is non-op.

I switch between hot and cold manually by moving the lever down low on the passenger side under the dash.