Elusive Electrical Gremlin

[diesel_dave]

DD,
Did you ever find a solution to this a/c blower problem? I took my M1151A1 out for a test drive yesterday and my rear evaporator blower kept cycling on/off every few minutes.

Yep it's a dying relay in my engine start box. I just give the box a kick and it works for a few more weeks.

 

[Autonomy_Lost]

DD,
Did you ever find a solution to this a/c blower problem? I took my M1151A1 out for a test drive yesterday and my rear evaporator blower kept cycling on/off every few minutes.

So interestingly my m1151 does this as well, but zero other issues. Just the rear evap fan kicks off every once in awhile, then turns back on after a minute. The front fan stays on and nothing else on the truck malfunctions. It seems weird that something with the start box could cause this specific issue. Maybe there is a relay inside the rear unit that is going out? Or maybe its part of the design for some weird reason?

 

[REF]

Next time the evap fan kicks off, pop the hood and see if your AC compressor is running. If the evap and comp are going on and off together that is normal.
The front fan (I am guessing condenser fan) should stay on as long as the switch is on high or low speed.
If your not fast enough with the hood don't worry just sit and watch I bet the net time the compressor kicks off so will your evap fan.

Edit; FYI the info is based on a guess that you have the evap and condenser terminology reversed, The unit mounted outside is the condenser and the evap is on the inside of the cab.
hope this helps

 

[HoveringHMMWV]

Next time the evap fan kicks off, pop the hood and see if your AC compressor is running. If the evap and comp are going on and off together that is normal.
The front fan (I am guessing condenser fan) should stay on as long as the switch is on high or low speed.
If your not fast enough with the hood don't worry just sit and watch I bet the net time the compressor kicks off so will your evap fan.

Edit; FYI the info is based on a guess that you have the evap and condenser terminology reversed, The unit mounted outside is the condenser and the evap is on the inside of the cab.
hope this helps

Just to clarify.... For my M1151A1, occasionally the rear inside unit blower (evaporator fan) shuts off while the front inside inside blower (evaporator fan) keeps running. I have not checked the under hood compressor or the left/right wheel well condensor fans during this.