P30 Chassis Dash Air Problems

[mikwallace]

Background: 1996 Winnebago Adventurer, P30 Chassis w/7.4L engine and SCS/ Frigette air conditioner. I've owned since 2009 and AC refrigerant has always had small leak. Before each trip I'd add one or two cans 134A refrigerant and bring pressures up to spec and AC worked fine for the trip. Usually took about a week before enough refrigerant leaked and AC wouldn't work. Also, plenum on firewall around Evaporator and heater core was cracked and pieces missing so temp fixed that with duct tape. Last week before a trip, I added refrigerant brought up to correct pressures, but it wouldn't blow cold air, only cool air. Never had that issue after charging. I decided to purchase plenum and find leak, repair and forever be happy. Cost of new plenum too expensive (more than 10% of the value of the whole rig), so I decided to remove and repair the plenum (repair went great and looks good). Determined refrigerant leak was at compressor, so bought new compressor, dryer, expansion block (THX), and AC flush. After removing compressor dryer and thx, I flushed both Evaporator and Condenser, put everything back together and pulled vacuum. Let vacuum sit appropriate amount of time to be sure leak was not present. Charged system. But still won't blow cold air??? Air in duct only down to 60 degrees.

So, AC experts please chime in!! What am I missing? Why won't it cool??

[dali]

I had a 1991 P30 Winnie and the air was working great then one day..then the next barely cooled the air. Found that there was a vacuum leak. the vacuum leak will make the heater water control valve not shut off and put hot engine temp hot water into the heater core that heated the cooled air. so... I would check to make sure that the heater water control valve is closed (is the heater hoses going to the heater box hot?).. if it isn't closed then you either have a bad valve or vacuum leak and your air may be working just fine.

[mikwallace]

Thanks to your comment and a vacuum hose diagram, I found the switch on the temp control was not closing the water valve. I adjusted that so water valve closes, but still no cold air. I even bypassed the heater core completely, but still no cold air.

Every solution leads back to the expansion block. Although it's a new expansion block, I'm beginning to think it's the wrong size. Parts list from Winnebago calls for a 2 ton block, so I ordered one from Comfort Air that has the part number shown on Winnebago parts breakdown.

It'll be here next week and we'll see??!!

[mikwallace]

Replaced expansion block and duct temp only gets down to 58 degrees, but air temp is 95. Have trip coming up and will see how it does going down the road. If this doesn't cool now the only thing left is the condenser.

[mikwallace]

Finally, all is working well. Took a beach trip two weekends ago and 38 degree air coming out vents. Copilot now complaint it's too cold!!

Then yesterday we traded for a 2006 Tiffin Allegro Bay!! Will pick it up next weekend.