Humvee M1152 ac problem

[DLippert]

When my heater is on and I switch to ac I hear a click under the dash the gage surges and the blower shuts off. When I switch back to heat it takes a couple seconds then the blower comes back on. Any help would be appreciated thanks

 

[Milcommoguy]

When my heater is on and I switch to ac I hear a click under the dash the gage surges and the blower shuts off. When I switch back to heat it takes a couple seconds then the blower comes back on. Any help would be appreciated thanks

My guess is a short circuit in the system or a weak breaker. The guage surge ??? more likely a dip in voltage, is my 2nd guess. The click could be the self-resting breaker behind the dash.

All guessed out. Saving the third one for after the commercial, CAMO

 

[DLippert]

My guess is a short circuit in the system or a weak breaker. The guage surge ??? more likely a dip in voltage, is my 2nd guess. The click could be the self-resting breaker behind the dash.

All guessed out. Saving the third one for after the commercial, CAMO

yes voltage gauge dips down for a second. Heater also will not blow hot air even after engine is up to temperature. Vehicle sat for a long time. I’m guessing the heater core probably needs flushed also.

 

[DLippert]

yes voltage gauge dips down for a second. Heater also will not blow hot air even after engine is up to temperature. Vehicle sat for a long time. I’m guessing the heater core probably needs flushed also.

when working correctly does the compressor kick on instantly after switching to ac?

 

[Mogman]

That system has an electric heater water valve that is notorious for failing, many just replace it with a manual valve.
It does sound like you have a short, it is time to download the AC schematics and start to troubleshoot the problem by disconnecting all the components and then re-connecting them one at a time until you locate the short, continuing to switch into the short can damage wiring, switches, circuit breaker and other components.

 

[DLippert]

Thank you

 

[DLippert]

That system has an electric heater water valve that is notorious for failing, many just replace it with a manual valve.
It does sound like you have a short, it is time to download the AC schematics and start to troubleshoot the problem by disconnecting all the components and then re-connecting them one at a time until you locate the short, continuing to switch into the short can damage wiring, switches, circuit breaker and other components.

Where is the valve?

 

[Mogman]

Passenger side of the fire wall.

 

[HoveringHMMWV]

This is what it’ll look like…..

 

[Retiredwarhorses]

When my heater is on and I switch to ac I hear a click under the dash the gage surges and the blower shuts off. When I switch back to heat it takes a couple seconds then the blower comes back on. Any help would be appreciated thanks

if The blower is working on heat but not AC? It’s not the blower…it’s the same blower. I had a truck in from DOE that did this and it was the EESS box was bad, also seen similar issues due to chafing on the body harness due to the 400amp generator.
You need further TS to isolate.

 

[DLippert]

I found the short in my ac system. The thermostat on the side of the front ac unit. Unplugged ac would not trip the automatic breaker and power is going to the heater core shut off valve now, plugged in it trips. Hopefully I’ll instal a new one and there’s no other problems. # 4 in the picture. The eess box was bad, the new one has another plug connection with a cap on the side. Just curious what it is for?

 

[Retiredwarhorses]

I found the short in my ac system. The thermostat on the side of the front ac unit. Unplugged ac would not trip the automatic breaker and power is going to the heater core shut off valve now, plugged in it trips. Hopefully I’ll instal a new one and there’s no other problems. # 4 in the picture.

you can bypass that thermostat for testing, plug the male and female packard plugs into each other,the compressor should run in the AC position.
if it still trips? The thermostat is not the issue.

 

[DLippert]

I did try that briefly it did not trip. I will do it again today to see if the compressor will kick in. The thermostat did have a dead short in it. This humvee sat for a long time it has 325 miles and 35 hours. It’s a good and bad thing but this is the last bug, the ac. Thank you for all your help.