Front A/C blower broke. Tried lots of stuff but, now STUCK

Thanks for reading this! --Using my Chilton's guide I first checked the fuse 0k,I also checked the relay under the glove box, but when it was taken out the REAR air did not work so I assume it is ok and has has no control over the front blower.I then hooked the blower fan direct to the battery and it fired up just fine. No grindy noises or screeching. I then removed the resistor coil *** and except for some rust on the bottom of the coils where they attach to the base it looked ok- but I replaced it with one from the junkyard anyway-- no luck! No blower! So I pulled the multi control panel which-- by the way, works ok when pushing the various air direction change buttons and rear defrost-- just no blower at any speed.Anyway, I relaced the whole control switch assembly. but still no blower up front. NOW I am stuck! Can you help?

From your description, the remaining single element that can cause your trouble and that you did not mention is the high speed relay, just beside the resistor bank.
http://www.avigex.ca/xport/heaterrelay.jpg
http://www.avigex.ca/xport/hvac_diagram_front.jpg

All fan speeds feed through that relay, low speeds through resistors when deenergized, and high speed direct to 12V when energized., all of this based on 90/96 diagrams....I suppose you car is in that range...

By the way, since you are a newcomer, let me invite you to browse through files I make available here: www.avigex.ca/xport/index.txt

Thank You for your reply. I have already used your helpful diagrams to get this far. I will check this out now and get back to you --

I opened the relay and it has a melted metal prong. Also the harness that attaches to the relay has an overheated wire that must have really got hot because the socket assembly that attaches to the relay will have to be replaced.It is burnt! I am not sure how that can be safely done. Maybe I could extract one with wires attached from a parts car and splice it to the wires after I cut the burnt one off. What do you think? Also, do you think I should worry about how the wire got burnt in the first place? I just bought it last week. I cannot imagine that having happened without blowing the fuse. The old owner must have replaced it.

THe solution you offer is OK; too bad you have to go to that length....by the way, you could just splice wire "dark blu"(87A) direct to "pulple"(30) around the relay and (if motor tested OK) run on all lower fan speeds without the relay....for a little while if you want to take the time to figure it all.....

THere is no fuse involved in the HIGH SPEED circuit: the juice comes direct from the 12V through the fusible link that endures. THe blower motor draws over 25 Amps on HIGH, which is a hefty load and on all of my cars I always consider this speed is for short bursts only. Slightly corroded contacts will develop a lot of heat at high load and with time can melt plastic and metal,
. Such a small motor at 25 Amps @ 14V (350 watt) is like your engine on nitro..... it will not sustain that regime indefinitely (run it one step lower and it will run for ever) ; at 25 amps for a long time, it can develop internal shorts between windings because the heat will crack insulation and then it will go to much more than 25 amps....and this is probably what has occured...meaning....I would check the AMPS to the motor when running on 12V..you said you had tried it direct from 12 V..do it again and just insert an ammeter to read the amps. IT has to be measured that way (the characteristics of a DC motor is such that measuring the resistance at rest will always indicate like a short-circuit and this is meaningless.)...

Thanks for the reply.The three smaller guage wires are the blue ,black ,and orange ones. There is a larger guage red wire and the wire that overheated and melted the prong inside the relay is the thicker purple one. You say I could splice the purple to the blue and that would give all speeds but the high-- Right? What is the role of the thick red wire?

Thanks for the reply.The three smaller guage wires are the blue ,black ,and orange ones. There is a larger guage red wire and the wire that overheated and melted the prong inside the relay is the thicker purple one. You say I could splice the purple to the blue and that would give all speeds but the high-- Right? What is the role of the thick red wire?
COnnect blu to purple as said and all 3 lower speeds will work.
THe RED is the direct feed from the battery that is used only for HIGH speed when the relay is energized.. SO it can stay unconnected for the time being.

Black is the ground for the relay coil
Orange is the 12 v signal for the relay coil.

Thank you folks for discussing the blower problem on the forum. My friend just asked me for help with his 95 Transport. I have learned a lot of good information from your comments. His blower is also dead. I was ready to replace the blower, but reading your discussion opened a lot of new things for me to check.

I'll post a reply once I get more information on my friends 95.
Thanks,
Kevin