Maybe Odd AC issue

[BeepJeep]

New here not new to Jeep….

21 Gladiator v6 gas 70k miles well maintained

recently noticed AC under performing all of sudden. The speed of the fan would not match output. The speed would be set at 6 for example then 30 mins or even sometimes 10mins the speed would gradually reduce and feel like a 3. The air temp would be set at LO but would feel like 75. It sounded like majority of air was being blown and trapped behind the dash no matter the vent setting. No change in vent setting would fix the noise until reset (see below) Most days operated as it should. Blender door operates as it should.
one thing to note this happens on AC and recirculate. Cabin filter is good. Not speed dependent. No lines frozen.

I know about the random burst Of warm air, this is not that as I’ve already disabled that feature by unplugging that motor that flips the vent cover down.

one Thing I did notice is when the fan speed would begin to slow down and I could feel warmer air I would shut the whole system off, wait 10 secs and power back on to which it would be normal again sometimes 10 mins to 30 or even rest of day.

So today during a couple hour road trip it started doing it again during heat of the day so I pulled the glove box. When feeling around you will see in the picture where I reached my hand I heard air rushing to which I felt in the area and the air was HOT. Like extremely hot. I could feel hot air blowing in this area.

anyone else experience this? I tried a search and found a few similar threads but nothing with the notation of extremely hot air in that area.

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[81Mojave]

Well the silver hard lines go to and from your heater core. I don’t believe the flow of coolant ever stops, so that area will always be warm. I could be wrong though.
Do these issues happen with temperature set and in auto?
What trim is the truck?

 

[BeepJeep]

Happens even in auto.

yea the core lines do run in that area but there is constant rushing of hot air right in that spot

Sport S

 

[Hootbro]

The fan speed is regulated by the HVAC controller via a Pulse Width Modulated (PWM) signal. You would have to use a scope to check the square wave signal on what is being sent to it from the HVAC controller to see if the HVAC controller is commanding it to vary speed or if the motor is heating up and causing a varying speed. There is no blower motor resistor setup like it is in the JK and older vehicles.

There is a TSB to update the HVAC software that address the hot air blowing issue and couple of other things. Whatever you disconnect for the hot air blowing issue may also be messing with how the HVAC controller processes HVAC function and is defaulting to some unintended default strategy.

Me personally, I would have the TSB done for the HVAC controller software and hook everything back up to re-baseline and go from there before trying to troubleshoot this as you may be chasing your tail on a self induced problem and not know it. Since you are beyond the bumper to bumper 3/36 warranty, it will be out of pocket at the dealer to get done. The TSB is listed as a 0.2 hour labor time but your dealership may have a minimum hour time charge.

 

[ShadowsPapa]

The fan speed is regulated by the HVAC controller via a Pulse Width Modulated (PWM) signal. You would have to use a scope to check the square wave signal on what is being sent to it from the HVAC controller to see if the HVAC controller is commanding it to vary speed or if the motor is heating up and causing a varying speed. There is no blower motor resistor setup like it is in the JK and older vehicles.

There is a TSB to update the HVAC software that address the hot air blowing issue and couple of other things. Whatever you disconnect for the hot air blowing issue may also be messing with how the HVAC controller processes HVAC function and is defaulting to some unintended default strategy.

Me personally, I would have the TSB done for the HVAC controller software and hook everything back up to re-baseline and go from there before trying to troubleshoot this as you may be chasing your tail on a self induced problem and not know it. Since you are beyond the bumper to bumper 3/36 warranty, it will be out of pocket at the dealer to get done. The TSB is listed as a 0.2 hour labor time but your dealership may have a minimum hour time charge.

^^^^^^^^^^^^^
what he said.
And thank goodness the old system of resistors to control fan speed is long gone. What a waste - slow a motor down by generating heat? Ugh. I was surprised our Liberty when we owned it still had a motor speed resistor. .

Can't say on this one for sure, but many many systems have no heater core valve and circulate coolant through the heater core all the time and simply use "doors" to close off the air through it, etc.

 

[Minty JL]

@ShadowsPapa yeah GM could never engineer those resistors right the first time

 

[TXJeepDad]

New here not new to Jeep….

21 Gladiator v6 gas 70k miles well maintained

recently noticed AC under performing all of sudden. The speed of the fan would not match output. The speed would be set at 6 for example then 30 mins or even sometimes 10mins the speed would gradually reduce and feel like a 3. The air temp would be set at LO but would feel like 75. It sounded like majority of air was being blown and trapped behind the dash no matter the vent setting. No change in vent setting would fix the noise until reset (see below) Most days operated as it should. Blender door operates as it should.
one thing to note this happens on AC and recirculate. Cabin filter is good. Not speed dependent. No lines frozen.

I know about the random burst Of warm air, this is not that as I’ve already disabled that feature by unplugging that motor that flips the vent cover down.

one Thing I did notice is when the fan speed would begin to slow down and I could feel warmer air I would shut the whole system off, wait 10 secs and power back on to which it would be normal again sometimes 10 mins to 30 or even rest of day.

So today during a couple hour road trip it started doing it again during heat of the day so I pulled the glove box. When feeling around you will see in the picture where I reached my hand I heard air rushing to which I felt in the area and the air was HOT. Like extremely hot. I could feel hot air blowing in this area.

anyone else experience this? I tried a search and found a few similar threads but nothing with the notation of extremely hot air in that area.

Did you ever find a cause or fix?
Mine just started doing this nonsense lol

 

[HooliganActual]

Did you ever find a cause or fix?
Mine just started doing this nonsense lol

One of my current Wranglers started to do the same thing a few months back. It was a typical failure mode of the control board. In previous Wranglers you could just replace the board but on the 2016’s and up, the board was built into the motor/fan assembly. I replaced the motor/fan assembly and it’s been right as rain since.

I don’t know how similar my 2016 Wrangler and the JT’s are but based on the symptoms I’d wager it’s the same.

 

[FloridaAussie]

One of my current Wranglers started to do the same thing a few months back. It was a typical failure mode of the control board. In previous Wranglers you could just replace the board but on the 2016’s and up, the board was built into the motor/fan assembly. I replaced the motor/fan assembly and it’s been right as rain since.

I don’t know how similar my 2016 Wrangler and the JT’s are but based on the symptoms I’d wager it’s the same.

Do you happen to have the part number laying around for the motor/fan assembly? This problem just happened to me today.

 

[HooliganActual]

Do you happen to have the part number laying around for the motor/fan assembly? This problem just happened to me today.

I may be misunderstanding your request, but I had replaced a fan motor on a 2016 Wrangler…is that the p/n you want? If it’s the p/n for the Gladiator you want, I have no idea but a quick google search for “Jeep Gladiator Blower Motor Replacement” will get you there.

 

[FloridaAussie]

I may be misunderstanding your request, but I had replaced a fan motor on a 2016 Wrangler…is that the p/n you want? If it’s the p/n for the Gladiator you want, I have no idea but a quick google search for “Jeep Gladiator Blower Motor Replacement” will get you there.

Hey Robert, thanks for getting back to me! I think I misread or misunderstood your original post; I was thinking you'd replaced it in the gladiator. Thanks again for letting me know!

 

[HooliganActual]

Hey Robert, thanks for getting back to me! I think I misread or misunderstood your original post; I was thinking you'd replaced it in the gladiator. Thanks again for letting me know!

NP, yeah I was just saying that I had the same problem with my Wrangler and what it turns out the issue is is that the control board on these units can go bad. In the older Wranglers, the board was separate but on the newer JK’s, the JL’s and the JT’s the board is now integrated into the blower motor assembly; so the whole thing has to be replaced.

 

[FloridaAussie]

Cheers mate. I speak English, American and Australian. I would not say I am fluent in the first two.

I drove my Gladiator a couple of times today and it worked perfectly. I feel like it's going to lull me into a false sense of stupor, and slap me as soon as I hit the highway back home next week.

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