classctioga73 wrote:
So this morning I took the rv for a ride. It blew cold air for about 5 minutes then just regular temperature air. I turned the knob to off and tried to turn it back on and no air came out at all. I turned the setting to floor and it worked. I turned the knob to off and back to vent and no air, then I turned it to floor and no air
Are these symptoms all related to a bad blend door box??
It still has freon in it, otherwise it wouldn't cool at all. If it were my rig here is what i would do.
Open the hood engine off, locate the AC compressor and become familiar with the clutch mounted on the end. Have an assistant start the rig then turn on the A/C. See the clutch engage. Now have them duplicate the scenario that you described, always watching the clutch. If they experience no air and the clutch is still engaged then I would focus on the door mixer. If the clutch disengages it most likely has air in the system and is building up high head pressure in the compressor. They kick off around 300 psi on refrigeration systems not sure on autos.
Easier way is to go to auto store that loans tools, you need gauges for 134a. You can't put them on wrong, the ports are sized differently.Install those start the engine and observe the pressures. Look up a basic R134a temperature pressure chart and you can see the numbers that you are aiming for. Ambient temperature changes everything. They offer cans now with a hose attached that works well however an air conditioning system does not use freon like an engine uses oil, you have a leak somewhere. One of my cars used a can a year. With the gauges on you can observe the high side(big numbers PSI) and the low side . If the low side goes into a vacuum you need freon, if the high side goes to a big number and the clutch disengages then you have an issue with air in the system.
The gauges won't blow up. Be sure they are in the off position before you start and leave them there. Check for that sight glass too. Usually mounted low, like bottom of radiator low about dime size glass. If the engine has been running for 5 minutes and there are bubbles, you have troubles.