M1165A1 Blower wont turn on - heat or a/c

[tgejesse]

I've been messing with my truck for the past few hours and I cannot figure out for the life of me why my heat/ac blower wont kick on.

I have bypassed the thermostat, but not getting any voltage at it.

There are 3 fuse boxes behind the batter box, only 2 have fuses - tried switching those around - no luck either.

There is a birds nest of 8 capped off wires that I cannot identify their purpose.

Electrical gods, please help lol

 

[Mogman]

What model/ser# truck do you have, this will help folks guide you to the correct information.

 

[tgejesse]

What model/ser# truck do you have, this will help folks guide you to the correct information.

M1165A1 SN 258xxx

 

[HoveringHMMWV]

I have a similar truck with those fuses too. But they were cut during demil and are not needed for a/c or heat. Those were probably used for systems that were removed during demil (heated windshield, turret power, etc...). As for the capped off wires, posting the tag numbers (metal crimpted thingies near the end) would be extremely helpful. The complete vehicle wiring diagrams are in the last pages of the maintenance TM ###-24-2. I'll attach a comprehensive wiring number list if I can find it.

 

[tgejesse]

I have a similar truck with those fuses too. But they were cut during demil and are not needed for a/c or heat. Those were probably used for systems that were removed during demil (heated windshield, turret power, etc...). As for the capped off wires, posting the tag numbers (metal crimpted thingies near the end) would be extremely helpful. The complete vehicle wiring diagrams are in the last pages of the maintenance TM ###-24-2. I'll attach a comprehensive wiring number list if I can find it.

Thank you!

Also where is @Retiredwarhorses when ya need him?! haha send help

 

[Retiredwarhorses]

Thank you!

Also where is @Retiredwarhorses when ya need him?! haha send help

your beater/evap blower is a Engel power wire and a ground…if it’s not blowing, make sure the wire is connected, it’s on the evaporator mid way down on the left side.

 

[tgejesse]

your beater/evap blower is a Engel power wire and a ground…if it’s not blowing, make sure the wire is connected, it’s on the evaporator mid way down on the left side.

All appears to be in order. There’s one ground wire terminated on the side half way down.

 

[Retiredwarhorses]

All appears to be in order. There’s one ground wire terminated on the side half way down.

Check the wiring behind the instrument cluster

 

[tgejesse]

Check the wiring behind the instrument cluster

Now this is a place I have not yet looked. Will check and post an update tomorrow!

thank you!!

 

[DREDnot]

Here is the wiring diagram I've been using.

 

[tgejesse]

Check the wiring behind the instrument cluster

Everything seems kosher back here too

I just confirmed that I have 24v at 400D so I'm assuming I have a bad blower motor..... but the rear evap unit isnt blowing either.

 

[Retiredwarhorses]

Everything seems kosher back here too

I just confirmed that I have 24v at 400D so I'm assuming I have a bad blower motor..... but the rear evap unit isnt blowing either.

have you verified the circuit breakers are still in the truck? I had a truck where they were pilfered.
they are in the battery box rear wall, there are 2 Klixon breakers on a bracket…

 

[tgejesse]

have you verified the circuit breakers are still in the truck? I had a truck where they were pilfered.

There are there!

 

[TOBASH]

There are there!

Have you verified they are properly functional?

 

[Retiredwarhorses]

There are there!

ok, well….the rear evaporator fan won’t run till the compressor runs, the front will run regardless because it’s also the heater blower motor.
Run 24v direct to you blower motor to test it…

 

[tgejesse]

Have you verified they are properly functional?

I have not, what would that procedure look like?
Also isn’t 24v at the blower motor and it not running a tell-tail sign that it’s a bad blower motor at a minimum?

 

[Coug]

I have not, what would that procedure look like?
Also isn’t 24v at the blower motor and it not running a tell-tail sign that it’s a bad blower motor at a minimum?

Not sure the specifics of how it's wired, but I assume the motor has 2 connections; one for power in and the other ground.

If you have 24V at the motor, and then have continuity from the other side of the motor to ground, it's likely a bad motor.
Of course you can check to see if the motor itself has continuity. No idea what the resistance is supposed to be, but it shouldn't be very high.

The motor could be good, and just a bad ground wire and give you the same results as a bad motor if you don't check.

 

[tgejesse]

Not sure the specifics of how it's wired, but I assume the motor has 2 connections; one for power in and the other ground.

If you have 24V at the motor, and then have continuity from the other side of the motor to ground, it's likely a bad motor.
Of course you can check to see if the motor itself has continuity. No idea what the resistance is supposed to be, but it shouldn't be very high.

The motor could be good, and just a bad ground wire and give you the same results as a bad motor if you don't check.

Update - the entire ac system is seized up. The motor was totally shot, and so are the condenser units.

Sad time to be me.

 

[tgejesse]

Here is the wiring diagram I've been using.

View attachment 906968

Additional thought exercise here to ensure I don't have other issues at play.

I am trying to get the rear evap assembly to kick on - and if I'm reading the diagram correctly if I bypass high pressure switch and ac compressor by connecting 436B directly into 7J - it should kick on, but it does not.

This made me start digging a little farther to see if I was getting any voltage at 236B, and nothing! I checked 720A to ensure I am getting 24V and I am into the rear evap assembly and it is.

Is 416D out of the evap part of the circuit to kick on the assembly in any way? Or is it safe to assume that if I have 24v in at 720A and nothing out at 436 B, the rear evap assembly is shot too?