Rear Heat

[dobaroy]

The rear heat in our 03 Safari is blowing cold, the front heat is pretty warm. Don't know where to start to find the problem. Any suggestions would be appreciated. Thanks

[CaptSquid]

Try bleeding the rear heater coil. The connections are under the passenger footwell.

[chesehd]

It might be easier to start with checking the vacuum tubes.

Under the hood, passenger side. If they're original I'm surprised they lasted this long.

[CaptSquid]

Chances are that if you have front heat, then the vacuum lines are not corrupted. HOWEVER, it's not a bad idea to replace the vacuum lines, as they may be just barely hanging in there. That, and it's not an expensive fix. Just purchase about 1 m of vacuum tubing from your local parts jobber. It'll take you about 15 minutes to replace almost all of them. If you replace the line from the intake manifold, then add another 30 minutes (for removal and reinstallation of the canine residence).

[Drummernaut]

Chances are that if you have front heat, then the vacuum lines are not corrupted.

I disagree. I had this exact problem. There is a vacuum control valve on the passenger side of the motor compartment below the blower.

A couple of years ago I fixed the vacuum lines in that area including the one that comes over from the intake manifold and my rear heat has work perfect ever since.

[dobaroy]

Thanks guys for all the replies. Would love to get into replacing the vacuum lines but where we are, we are going through a cold spell but plan to get at it as soon as we can.

[Drummernaut]

My first problem was the short line from the solenoid to the valve, it was Swiss cheese. I later had to replace the line going to the top of the solenoid which is the long one. You can start with the short one and hope you are lucky but chesehd was right, were there is one bad vacuum hose then all hoses are bad. Especially the plastic ones.

If you have good vacuum at the valve but still no rear heat then that valve may be bad. You can ad any vac to that valve and if it works you will start to feel the hose warm up as the water flows.

Good luck.

[chesehd]

If I recall correctly, there was a problem regarding my rear heat valve solenoid on my '03. From what I can recall, I was able to bypass the solenoid and just place the vac tube directly on the lowest port and keep the heat working. I'm done for the night so I'll try to verify tomorrow.

[Drummernaut]

You can bypass the solenoid but if the short line going between is bad then the long plastic one going to the top connection is probably brittle along with the rest of the lines. Like you said, some vacuum line maintenance is probably needed. The solenoid is probably fine.