'96 Transport AC Fan Quiting Intermitently

[trjones]

The fan on our '96 Transport is now going off and sometimes staying off for long periods of time, and then will mysteriously come back on. Makes it uncomfortable here in the ol' Midwest when the temps are approaching zero. My neighbor came by to look for the fan, which is on the firewall in the engine compartment, and he listened to it running an said it sounded fine, so he didn't think the bearings were going out in the fan. Any suggestions as to what else could be causing this?

[LMP]

Is this a fully electronic automatic temperature control (was it available in the '96 transport, tell me?) ?

[trjones]

I don't know how you classify it. You have to move the temp lever left or right for cold to hot, but you cannot set a temp for it to maintain if that is your question.

[LMP]

Yeah OK that was the question and the answer is clear. Thank you...This is conventional control.
I'm looking for the diagram....in the mean time....you mean it will not rotate at ANY speed when it decides to go haywire?

[trjones]

Correct.

[LMP]

OK first check for the relay known as "low speed relay" shown here in the "convenience center"
www.avigex.ca/xport/convenience_center.jpg
(this is from the '93 service manual)
THis relay feeds 12V to the blower switch so it acts on all speeds.
The horn relay is probably exactly the same: switch them one for the other and see what happens.
ITs position might be slightly different but mostly the same..the '93 and '96 are very similar

[trjones]

It's hard to tell from the drawing, but are these relays under the dash or by the fuse panel?

[LMP]

Other possible cause: the blower switch itself. Since it does not opeate at ANY speed, the HIGH SPEED RELAY or the resistor bank cannot be blamed because some speeds would work, and not some others then .
www.avigex.ca/xport/heaterrelay.jpg
Check all connectors

[LMP]

Originally Posted by trjones

It's hard to tell from the drawing, but are these relays under the dash or by the fuse panel?

UNder the glove box

[trjones]

Thanks, we'll give it a try.

[LMP]

Here is the complete diagram for the front blower
www.avigex.ca/xport/hvac_diagram_front.jpg

and for the rear blower (single control)
www.avigex.ca/xport/hvac_rear_single.jpg

for the rear blower (with front and rear controls )
www.avigex.ca/xport/hvac_rear_dual.jpg


EDIT: ONE TEST I should have asked from the start: when the front blower stops working, does the REAR blower continue to work?
- if rear stops too, then it is most surely the relay
- if rear blower continues working, then the relay is OK