HVAC blower problems

[mws]

One other problem with my Pathfinder is the blower for the HVAC. It only works on postion 4 (hurricane setting). The pathy is an '87 XE, pretty much baseline with V6.

 

The previous owner had a little fire (if there is such a thing...) under the dash on the passenger side on a hot day with A/C cranking. Turns out the resistor pack module overheated. Severe enough that a big chunk of the HVAC plenum box is melted away. That's easy to fix.

 

BUT, after a couple hours with a multimeter and some jumpers, I still can not figure out to fix the blower speed control so I can get a lower fan speed. I'm still trying to find a factory shop manual, so thought I would try you guys.

 

Here's what I know:

I do have the (borderline useless) Chilton manual and the schematic in it.

 

The toasted resistor module was removed and tossed and I have not been successful in finding a new one (may have to get from $tealer or fab my own). In the meantime, the Chilton schematic indicates I should have been able to jump across terminals in the resistor module connector and the fan would run (at full speed) at with switch at settings 1,2, or 3. No luck. Still only runs on 4 only.

 

The A/C compressor appears to funtion fine when switch is pushed, but the light does not come on in the switch. The bulb tests OK. (Clue?)

 

Probing the contacts on the dash contol switch revealed 0 volts at all terminals except the one on the far right - blue/white wire which is at 12V. That's odd. I expected the grn/blk to have 12 V.... (Clue?)

 

So I'm suspecting one of the other components upstream (downstream?) died. The Chilton schematic indicates there are several things -

- Thermo control amp

- Dual pressure switch

- A/C relay

- FICD relay

- Blower signal relay

- Diode

- ECCS control unit

 

Any ideas which I should analyze or replace first? And where it may be?

[denisb]

I've got a shop manual for the 88. I can send you the electrical part of the heater/ac if you're interested. It doesn't have values for the resistor pack, but if you're handy with a schematic, I'm sure it can be of help. If you want it PM me or e-mail me and I can scan it at work and e-mail it to you.

 

Denis

[mws]

A resounding YES to your offer! Many thanks! I just PM'd you.

Martin