Roof A/c Question

[wildtoad]

Hi there.. my 1988 Winnebago Superchief "project" has a 13500 btu roof air which I suspect is orig. It works and cools but not exactly adequate for here in the south in 100 degree weather. My question is what should one expect from a unit like this in regards air temp from the unit? I took a radio shack dual display thermometer. After running for about 30 minutes, the inside of the mh is still about 90 and the air coming from the A/C vents is in the high 50's to low 60's. Should I expect any better than this?

Thanks

[94-Newmar]

a 30 degree drop is fairly substantial.. they can be recharged you know! Have someone get some gauges on there and check it out. Meanwhile make sure to keep the windows covered with sunscreen type mesh, especially the front! We have older 13.5's on our Motorhome and having the same issue as you, 30-35 degree drop at the outlets yet still warm inside but after covering the front window it stays a nice 70 degrees (even cycles) on these 90+ days.

[Ernie Ekberg]

they can be recharged if a tech installs the valves on the lines. standard from factory units don't have these. guess they want you to buy a new one

[TXiceman]

A 31' RV is sort of the extreme for a 13500 BTUH A/C. WHne you have to replace it get a 15,000 BTUH to help a bit.

90% of the time, the units do not need refrigerant and while they can be recharged, it is not easy and not for the home mechanic. First check to see that the air filters are clean and the evaporator coil is clean. Low air flow due to restrictions is the biggest problem.

To check the unit, let it run on high for a good 15 minutes or more. Set the thermostat as low as it will go. Using a good thermometer read the air temperature at the inlet to the unit. Then check the air temperature leaving the unit. The air leaving the unit should be between 18 and 20 deg F lower than the air entering the unit. If you get that reading, it is doing all it can do.

If you are getting more like 30 deg F difference, I'd suspect an air restriction like a dirty coil or filter.

Let us know what you find.

A motorhome gains a lot of heat through the large windshield, so cover it with a sun screen or better yet, some of the bubble insulation with the aluminum film. park in the shade, keep windows covered and as much sun as possible off of the RV.

Remember that you are trying to cool a poorly insulated box with just a bit more than 1 ton of air conditioning.
Ken

[wildtoad]

Thanks for the notes... I have already cleaned the filters, have not checked coils but will do. I suspected a 20 degree drop in this weather was about as much as I could expect.

[RV Wizard]

One other and often overlooked issue is recirculating or short cycling of air from the discharge side back into the return. There is a divider that must separate the two. If need be; reseal. Ken is spot on, with the information he is providing.

[62Morgan]

He has two (2) 13,500 A/C units in this model. I owned the same 1988 Superchief model for 7 years. It's mostly a heat-gain problem due to sun exposure, single pane windows w/minimal weatherstripping and uninsulated front & rear caps. Corrective measures include cover windshield, side windows & renew felt for slider windows. The thin fabric Oem curtains alone do not do the job.

Don't forget to add skylight and vent covers (preferably insulated or foil-faced).