The cabin fan cuts off and on while A/C is cooling
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Mountain Pass
Joined: Apr 2020
Posts: 240
Likes: 30
From: NC Mountains
The cabin fan cuts off and on while A/C is cooling
Lordie, this rig of mine is makin me crazy. I have a 1996 F150 5.0 4x4 Eddy Bauer. I got it in 2019 and have done or had done MUCH mostly smaller issues. When I got it, one of the issues was A/C comp. was out. I got a decent one from junk yard also new accumlator. Added some Pag oil, Vac.ed it down added 134a and all was right with the world for about 3 weeks. Since that time I have replaced the evap.coil 2x, new line from cond. to evap.. and most recently repl. the cond coil. The dang thing kept spring leaks. I have had it up and running now for about 3 weeks. Now that the system seems to be holding,, as I drive about,,, not a great deal but It gets nice and cold in that small cab. Now for the "Hitch in the Get-Along" The cabin fan runs great for 5+ mins, then it stops blowing for 1+ min. then that cycle continues I have turned the temp up and down. ran it on normal A/C, Lowered fan speed, cracked windows down just a bit and no difference. Any thoughts on my latest "Corn-Fuffel" please share. .
Hotshot
Joined: Jul 2020
Posts: 10,400
Likes: 2,606
From: Near Salt Lake City
My guess is the motor
If the resistor goes out (thermal limiter failure) you will still have high speed
KICK smack (interrogate) the blower motor, if you can get it to quit or come back on, replace it
If the resistor goes out (thermal limiter failure) you will still have high speed
KICK smack (interrogate) the blower motor, if you can get it to quit or come back on, replace it
Thread Starter
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Mountain Pass
Joined: Apr 2020
Posts: 240
Likes: 30
From: NC Mountains
Yes,,, this fan has never done this while runnung vent,,, heat defrosr etc. This just started very shortly after the A/C replacement work
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Mountain Pass
Joined: Apr 2020
Posts: 240
Likes: 30
From: NC Mountains
So where would be your best guess to start looking for that leak?
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Fleet Mechanic
Joined: Jul 2019
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If it’s a design anything close to my ‘03, there’s a hose coming from the passenger side rear of the intake that tees off into the firewall. That hose was full of holes just from breaking down over time. It was intermittent for some time before it wasn’t and went full defrost.
Vacuum reservoir by the battery is also a spot to check, but the hose may be easier to get to.
Vacuum reservoir by the battery is also a spot to check, but the hose may be easier to get to.
Last edited by Johnny Paycheck; May 24, 2026 at 09:48 AM.
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From: Kentucky
As noted above the white vacuum line that goes to the recirculation motor is known to disintegrate if you look at it too long. The age and heat turn it to powder. Next up is the one-way check valve between the manifold vacuum port and a tee fitting. One side goes to the HVAC vacuum reservoir on the blower/heater core/evaporator box, the other goes to the control panel inside the cab.
For reference:
For reference:
Last edited by rla2005; May 24, 2026 at 12:31 PM.
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