M1152 AC issues

[Greasard.of.Oz]

Had to replace compressor as the serpentine belt destroyed the wires running to the compressor.
Compressor works fine now.
I only have front end AC, ran well for a while after recharging it, but seems to have a leak under passenger side unit, I thought it was condensation originally, but its quite a bit of what seems like water.
Currently AC only blows hot air, doesnt cool.

any ideas/suggestions on where to start here?
Any advice appreciated.

 

[Coug]

The valve to turn on the heater core flow is notorious for failing on the newer trucks with the electronic valve.
Most reliable repair is to replace the electronic valve with the manual one from the older trucks. Follow the coolant lines from the engine back into the firewall on the passenger side of the engine bay.

Leaking freon from aircon won't create any water or liquids like that, so most likely it is condensation.

The valve failing is a common issue and there are multiple threads about it here on the site, but I'm not at a point I can find them for you right now.

 

[mrfarb]

Agree with Coug here - mine was deteriorated inside so even when manually closed it allowed hot water into the heater core, making front a/c blow hot. As long as your a/c is charged and pressures are good, it’s working.

 

[Greasard.of.Oz]

I have zero experience with auto AC, learning from scratch.
Been trying to dig into technical manual with minimal success.

appreciate your replies!
Been searching the forums here as well.

I do not understand how the water relates to hot/cold air here, and the fact that there was a ton of water on the passenger floor when AC ran makes me concerned.
It was likely condensation, but could it be a leak in some water line?

sorry this is probably very dumb question, again, not a mechanic…

Thinking of i stalling a manual valve and check what happens.

 

[Greasard.of.Oz]

So upon inspection, valve looks fairly new, but
It looks like I am low on coolant somehow (I am surprised bc recently had it serviced by military mechanic and did not notice any leaks on my driveway)

should I fill coolant via cap on this reservoir? Prestone coolant? Or should I flush the whole system…

 

[mrfarb]

I’ll do my best to describe why - The front evaporator (looks like a radiator) and heater core (also looks like a radiator) share the same air housing - so the valve turns off the super hot water going to the heater core. If the valve is failed, air is going across the heater core before it hits the evaporator. Basically you are running very hot air over your a/c evaporator. My valve looked brand new, but the inside flap had a rubber component that was rotten, allowing hot water in there, making it blow hot.

Yes - that cap is where you add coolant. Use green coolant. Don't add it until you fix that valve as you will lose coolant.

You may try disconnecting that solenoid and manually closing the valve, sometimes that solenoid goes bad.