I have a 86 F150 5.0. My blower fan only works on hi tried changing out the fan used and new and had the same result. Ordered one each resistor from LMC and NPD both were the wrong part even though NPD has the correct part shown in the book for hi output heater they only had for the heater only without A/C. I got one from the junk yard and still got the same result. It's a obsolete part through Ford. I even found the manufacture ( INDAK) that make this resistor for motorcraft but only sell in large quantities. My question if possible to wire in a later model resistor a harness and would this work?

 

Because you tried a resistor cluster from a junkyard, and I assume you tested yours and the junkyard one with an ohm meter to verify that they were good, I'm thinking you have a wiring or blower motor switch problem. Have you run voltage tests at the resistor connector?

 

I've replaced the blower switch before moving to the resistor. Checked the resistor connection wires and it getting power to the motor except on low. I haven't checked the junkyard resistors. On the original resistor the single wire on the top was broken.

 

1990 F350 diesel with A/C - I can only get High speed on my heater fan. I replaced the switch. No change. What is the next step in troubleshooting this problem?

 

I would pull the resistors and test them since they are what controls the blower motor.

 

Today was a good day, last week I sent out a e-mail to two of the local Ford dealers I found out the resistor part number ( Motorcraft E3TH-19A706-AA) for the 86 F150 5.0 has change to ( 4C2Z-19A706-BA) according to the parts personel there are lost of dealers that still stock this part. I had both resistors check and both are bad.

 

What is the cost of said part?

 

Correction on the part # for the 86 F150 it is E3TZ-19A706-B Cost $20 after a year of calling salvage yards and online ordering I think this was worth it, I came out cheaper with the correct part. I pick it up yesterday and it's the exact same but it still carries the old part# (E3TH-19A706-AA) I put it on and all blower setting works.