Duotherm AC "valve stuck"?

[Scooby450]

Well, not that I need it, I do live in Arizona, my rear Duotherm 13.5 AC unit only blows hot air. Much like myself....the tech told me it has refrigerant in it and that the valve is just stuck. He suggested I run it for about 48 hours and, if I'm lucky, it may open up. According to him, if it doesn't work I will have to buy a new unit.
feedback?

If I get a new one would it be worth up-sizing? Is it a fairly easy install if I replace it myself. I do have aptitude...

Thanks!

[fxdave]

ive got one doing the same ! it does get colder but not like the front one ! ugh some one mentioned doing something to the valve i cant remember what !

[Rex]

Sounds like the reversing valve is stuck. You can tap it firmly with a screwdriver handle and it should release. The valve also has a solenoid that can go bad and that is replaceable, but the valve itself is not.

[Scooby450]

Great, what's it look like? I did see a schematic online. I'll check that. If it doesn't release I need to replace the unit?

[RV Wizard]

Has four copper refrigerant lines; two from compressor and one each to outside and inside coils.

[SUMDALUS]

Scooby 450,

You didn't state if your unit is a heat pump.

We're all assuming it is and the 'valve' referred to is a reversing valve. As Rex responded, the coil that controls the valve is, indeed, replaceable. However, great care should be when 'unbolting' the coil from the valve. If the bolt is badly rusted or frozen, you may accidently twist the valve and rupture one of the 'spider' lines connected to it. If that happens, all the refrigerant will leak out and you will definitely need a new unit.

The reversing valve is located somewhere close the compressor and fits RV Wizard's description. The coil usually has a brown bakelite cover, is "D" shaped, and has two wires attached to it that lead to the unit's control board. If the bakelite cover is cracked, the coil is bad.

By the way, Dometic heat pumps initially start in the "heat" mode. If the t-stat is calling for cold, it will 'reverse' into the "cool" mode. Coleman and Carrier heat pumps function just the opposite.

When the valve reverses, you should be able to hear a destinctive "clunk" sound coming from the unit.

[Scooby450]

Thanks for all the great responses! Yes, it is a heat pump unit. I doubt that it is rusted, I live in AZ. unless it is due to the moisture from the unit. This unit has very little use, I got the rig in '06 and haven't used it much where I need the AC until recently.

Dale, if the cover isn't cracked that does not mean the coil is good (just want to clarify-I am capable of testing it), you just meant that if it is cracked than it IS bad...right?

[jeepfreak]

If the reversing valve is bad , when the unit is running you should feel cool to cold air at the condenser on the roof , as it' just an a/c that runs the cycle in reverse.

[SUMDALUS]

Scooby 450,

Yes, if the cover is not cracked, you will need to do a conitnuity test on it to make sure it is still good. Continuity good = coil good. The bakelite cover will initially crack from excess current flow (heat) through the coil when trying to move a frozen valve. (This is why some people try wacking the valve with a tool - trying to loosen a frozen valve. Something I don't recommend.) Once the bakelite cover is cracked, corrosion will complete the assassination of the coil.

Once the coil is removed you should be able to move the valve in and out (up and down) easily by hand. If it moves easily when the unit is not running (no pressure on the valve), replace the coil. Otherwise replace the heat pump. Trying to replace the reversing valve is a significant challenge for the most experienced repair expert.

(p.s. A heat pump heats and cools - an A/C only cools. The terms are not interchangeable.)

Please keep me posted on your outcome.

[Rex]

Here is a picture of a reversing valve coil. Yours may be a bit different.

[jeepfreak]

I've been doing refrigeration and HVAC for 40 yrs and have never seen a sol. valve stem that can that can be moved by hand. The stem the coil slides over is a sealed part of the valve . On refrigeration , some may have a stem that has a cap that can be removed and manually opened but not a reversing valve. And it won't hurt to tap it lightly . Just don't remove the coil with the a/c on. Because if the coil is good it WILL burn out if it's powered and not on the valve.

[fxdave]

where might we find a replacement valve ?

[jeepfreak]

The valve could have a name on it possibly Sporlan or Danfoss or Parker. Maybe it would be on the coil . But this not an easy undertaking. You have to recover the refrigerant, unsweat the old valve, and if doing the job properly run nitrogen thru the system while brazing in the new one. Then evacuate the whole system and finally use an electronic scale to weigh in the proper amount of refrigerant as these systems are what we call in the trade critticaly charged. Unless you know someone that has the tools and knowledge I don't think it would be wise to try it. Maybe you could try an a/c service company and if you took it off the roof and brought the unit to them maybe they would do it. But I would find before removing it.

[jeepfreak]

Oh, sorry I didn't answer your question. You could try an RV dealer or maybe a HVAC/Refrigeration supply , don't know if they sell the general public though. Possibly an appliance parts . If you do go looking make sure you write down every number you find, model #"s and seriel #'s are VERY important!