2006 Granite A/C Trouble

[Chadro]

One of our dumps is a 06 Granite with the 370, I am terrible with A/C systems so I figured you all were the bunch to ask. Driver was complaining it was blowing ice cold but was barely blowing as well as it wouldn't drain unless you turned the blower motor off at which point it would just pour a crap ton water out. So if he didn't shut the blower off every 15 mins or so it would back up and drain water all over the floor of the cab. One of the mechanics put a new filter in and rinsed and blew the coil off as everything was clogged with dust. It started blowing a lot harder but still wouldn't drain right and the compressor started short cycling lol. The hooked it up and deemed it could be charged a little bit, they got it to around 315 on the high side and I can't remember the reading on the low side. Now it blows hot and the compressor only kicks on for a fraction of a second about every 10 seconds. I have no clue what the problem is but they are convinced it's just the expansion valve. Any ideas? lol

[41chevy]

When the units dump water into the cab it is usually a clogged external drain. Roof mount will be in the bottom rear of the unit and run down the back of the cab. Factory unit will generally have the drain tube coming through fire wall or toe board near the bottom of the HVAC unit.

Others may know the factory Numbers for the 134 system you have, but I learned as a rule of thumb, to set High side pressure a 125 over the out side temp. ( a 90 degree day the high side should be about 210 / 220 ) . Sounds like the unit is over charged and that will cause no cooling and the High Pressure switch to cut out and the compressor to rapid cycle. Paul

[Chadro]

Well turned out to be a bad expansion valve, nice and easy.