HELP!! 94 marq Heater not working

[noyz25]

The heat has'nt worked for a few weeks one of my friends moved a wire inside the dash somewhere and it worked for 2 days but now its not working again. what could this be??? i suspected the heater core at first but then my friend just moved a wire and it started working. i am dumbfounded and its very cold. please someone help me cause they are charging me too much just to diagnose the problem.

[fredjacksonsan]

Sounds like something is coming unhooked under the dash, ask your friend to show you what he did so you can duplicate it, or make a permanent repair.

[noyz25]

Originally Posted by fredjacksonsan

Sounds like something is coming unhooked under the dash, ask your friend to show you what he did so you can duplicate it, or make a permanent repair.

thing is he aint even sure what wire he really moved.

[fredjacksonsan]

OK, then take flashlight and have a look up under there, try to find the area he was messing around in. I'm not the best underdash man, but there are likely several vacuum fittings and push/pull rods under there that control the heat and AC. Check for any loose or unattached parts.

If he fixed it by accident once, you should be able to fix it on purpose.

[6502dude]

There should be two vacuum lines that come in thru a grommet in the firewall - above gas pedal on driver side. One is black and the other is white. One of these goes to emergency brake release control. The other (black as I remember) goes to a feed a primary vacuum motor in the plenum assembly. Vacuum is fed from there to the distribution control (attached to rear of heat & A/C controls in dash).

As FredJacksonan suggests, get a flashlight and have a look underneath dash. You should hear sucking sound from vacuum line if it has been disconnected.

Not only will you have no heat with an open vacuum line, but also your overall engine performance will suffer.

Just follow vacuum lines from grommet in firewall to make sure each is attached. The vacuum motor should stand out as a bare metal canister attached to plastic plenum assembly.

[noyz25]

After tampering with it checking that vacume hose i got some heat. its pretty warm now not hot. but it wont blow as much air as its suppose to either. any more advice ya can give me would be very appreciated.

[6502dude]

Fan speed control is based on blower motor resistor network located in engine compartment.

If speeds are missing, checking cabling from dash fan speed switch and connection on resistor network (mounts on assembly just below heater core input hoses). If wires are okay and switch id good - replace resistor network.

If heat temperature is not up to par, you may have a small vaccum leak, there may be a problem with the vacuum distribution control, your vaccum motor may be weak, your heater core may be clogged, etc.

Hope you kicked your "friend's" ass for screwing with under-dash without a clue with what he/she is doing.

[cobradude360]

id try a coolent flush or even a thermostat to mayb get it a lil hoter but to over all have nice clean coolent for ur engine