Help! Basement Air Problem

[gfs1943]

Basement air conditioner quit working on our 2000 Itasca Horizon. AC blower works. Compressors run, but condensor blower doesn't run. It will sometimes start and run a little while, then shuts off. Compressors continue to run until (probably) the high-pressure switch shuts them off because there is no cooling air. Sometimes when I turn on the AC, nothing runs except the inside blower. Sometimes, it works as described above.

The condensor blower spins freely, so it's not bound up. I suspect a circuit board problem, or a sensor switch problem, but can't say for sure. Any help appreciated.

Recently, at our last overnight stop, the AC would never work because the condensor blower didn't run at all. After we got home and hooked up to power, I turned the air on and the condensor fan ran about 75% of the time. It would start right after the thermostat was turned to a position demanding AC. While the unit was running, the condensor fan would shut off (compressors continued to run), then come back on after a few minutes.

I posted this question on another forum and got some suggestions about circuit boards, relays, and capacitors, but nothing I could really say, "Aha!" about. All help appreciated.

[Wizard]

Probably not going to be any "aha" moments without checking those relays and circuit boards as they control everything. Duner has a posting that helps with removing the unit for repairs but to get to the circuit board you just have to remove one small cover. That is after raising the grill hatch.

[SuperGewl]

do a search on the site for more info. Someone just had theirs replaced with a new one for $1500 - 2200.

[KIX]

Your basement A/C can be removed from the coach and remain connected to the t-stat and electrical. You can operate the unit while the top cover is off allowing you to diagnose any problem with the blower motor itself while it's operating. Other than that advantage all the electrical components such as capacitors, relays, pcb are accessible without removing the unit.
Also, I think you can find a service manual at RVcomfort.com

[UFO Pilot]

Have you checked the start capacitors? Remove the outside grill and there will be a small cover plate that can be removed. You can then check the electrical. Both my start capacitors were burnt out. The AC would start and then shut down.

[gfs1943]

Originally Posted by UFO Pilot

Have you checked the start capacitors? Remove the outside grill and there will be a small cover plate that can be removed. You can then check the electrical. Both my start capacitors were burnt out. The AC would start and then shut down.

Thanks to all for the suggestions. I have eyeballed the components inside that cover (looking for anything obviously burned), but have not tested anything. As soon as I get a good link to a source, I will replace the start capacitors and, probably, the relay for the condensor blower. I really don't think this is a capacitor problem because when the blower does run, it will sometimes run for 10 minutes before shutting down. But it does shut down with the compressors still running -- shouldn't do that.

I'm not an electronics expert, and don't have anything but basic test equipment, so this is gonna take some time. I do appreciate all the help from all you folks!

George Stewart

[DancinCampers]

I would check the connections on the small silver capacitor located with the 2 black compressor capacitors. I believe this is the outdoor blower motor run capacitor. I think the indoor blower motor run capacitor is located on the indoor blower motor.

Try running just compressor circuit number 1 and see if the outdoor blower motor stays running. This would be on low speed. Hi speed is when #2 circuit is running in cooling mode, and I believe is a separate relay.

[gfs1943]

Originally Posted by DancinCampers

I would check the connections on the small silver capacitor located with the 2 black compressor capacitors. I believe this is the outdoor blower motor run capacitor. I think the indoor blower motor run capacitor is located on the indoor blower motor.

Try running just compressor circuit number 1 and see if the outdoor blower motor stays running. This would be on low speed. Hi speed is when #2 circuit is running in cooling mode, and I believe is a separate relay.

Thanks for the tip, Dan. I will try this as soon as I get a chance.

Before this condensor blower stopped working properly, I did have the AC circuit breaker trip a couple of times on different days. The last time it happened, both the Circuit 1 and Circuit 2 breakers were tripped. I reset them. A few minutes later, Circuit 1 tripped again. I reset it, and everything worked well the rest of that night. A couple of days later, the problem with the condensor fan showed up.

[johnnyk]

You will probably need to get it checked out but I had a similar problem on my 2001 Horizon. In my case the outside blower would not kick into high speed mode but would just shut down which of course caused the HP switch to shut down. Sometimes it would run for a few hours and other times it would shut down in a few minutes. It just depended on the cooling load. It turned out that I needed to replace the circuit board. The tech was able to diagnose the problem without dropping the unit. I would look up an RVP tech in your area that can work on basement units.

John

[gfs1943]

Originally Posted by johnnyk

You will probably need to get it checked out but I had a similar problem on my 2001 Horizon...
John

Thanks Johnny. Your problem description sounds most like mine. I'm gonna look for a RVP tech around here (north Texas). May be hard to find.

I could do the work myself, if I could get the parts, but I can't keep the coach at my house for more than a couple of days. And I'm not as fast as I used to be!

George Stewart

[johnnyk]

The airxcel web page seems to list quite a few in the Denton area. I know other members have used residential A/C service personnel for service. It just depends on what you are comfortable with. I wanted someone to come out to the coach so I looked for a mobile tech.

[garyswann]

I noticed the condenser fan pauses when the second compressor starts. Must be to keep the amp draw down. I don't know if its on the board or a relay.

[Duner]

Originally Posted by gfs1943

Thanks Johnny. Your problem description sounds most like mine. I'm gonna look for a RVP tech around here (north Texas). May be hard to find.

I could do the work myself, if I could get the parts, but I can't keep the coach at my house for more than a couple of days. And I'm not as fast as I used to be!

George Stewart

George,
Do you have a friend or a location where you can work on it for a week or so? You will save yourself a ton of money if you can use the "Removal Procedure" I wrote. See my website below. Slide the unit out and pull the lid on the unit. Check the shaft on the Outdoor blower....chances are that the brass bearings are shot and the metal squirrel cage is cracked. The motor may be pulling too much power. I have all the troubleshooting doc from RVP and can send you the pdf's just PM me your email. The rvp stuff is very helpful to diagnose. And if you get stuck , most AC guys will be happy to work on the unit if it's already out and open.

Good luck,
Bill

[KIX]

Originally Posted by Duner

George,
Do you have a friend or a location where you can work on it for a week or so? You will save yourself a ton of money if you can use the "Removal Procedure" I wrote. See my website below. Slide the unit out and pull the lid on the unit. Check the shaft on the Outdoor blower....chances are that the brass bearings are shot and the metal squirrel cage is cracked. The motor may be pulling too much power. I have all the troubleshooting doc from RVP and can send you the pdf's just PM me your email. The rvp stuff is very helpful to diagnose. And if you get stuck , most AC guys will be happy to work on the unit if it's already out and open.

Good luck,
Bill

And, if you've got it out and open change the OD blower wheel to the new plastic composite one. It is noticeably quieter......more on outside.

[gfs1943]

Originally Posted by Duner

George,
Do you have a friend or a location where you can work on it for a week or so? You will save yourself a ton of money if you can use the "Removal Procedure" I wrote. See my website below. Slide the unit out and pull the lid on the unit. Check the shaft on the Outdoor blower....chances are that the brass bearings are shot and the metal squirrel cage is cracked. The motor may be pulling too much power. I have all the troubleshooting doc from RVP and can send you the pdf's just PM me your email. The rvp stuff is very helpful to diagnose. And if you get stuck , most AC guys will be happy to work on the unit if it's already out and open.

Good luck,
Bill

Thanks a million, Bill. I have the documents you wrote, saved on my computer. My problem is not having a location to work on the unit.

I don't suspect the bearings at this point -- the fan spins freely, and when it does run, it's quiet. But I'm sure that, whenever I get the unit out and opened, I may as well replace the blower and bearings to prevent trouble later.

[gfs1943]

Originally Posted by KIX

And, if you've got it out and open change the OD blower wheel to the new plastic composite one. It is noticeably quieter......more on outside.

Thanks for your help, KIX. I will do that when I get the unit out. Looks like I may have to remove the unit completely and disconnect all the wiring so I can take the coach back to storage while I work on the unit in my garage. When I get the blower and all the capacitors replaced, I'll reinstall the unit and hope it works! I'll make up a wiring block to simulate the thermostat 12V controls, and power it from my lawn tractor battery, to run the unit while I troubleshoot.

[Duner]

Originally Posted by gfs1943

Thanks a million, Bill. I have the documents you wrote, saved on my computer. My problem is not having a location to work on the unit.

I don't suspect the bearings at this point -- the fan spins freely, and when it does run, it's quiet. But I'm sure that, whenever I get the unit out and opened, I may as well replace the blower and bearings to prevent trouble later.

George,
Your unit is older than mine and if it's running nice and quiet now, then prior owner may have changed the bearings already.....is the squirrel cage metal or plastic? If plastic, ya they were in there since it was available in '05 or '06.

So problem is probably electrical and not mechanical. Suggest in the future, use a Hughes Autoformer to keep the voltage up around 117-120 vac. When it's hot and everybody in the rv park has their A/C cranking, it's common to have only 100-110 vac. That is really hard on all the motors and shortens the life of the starting circuits.

Good luck,
Bill

[gfs1943]

Squirrel cage is metal. I do believe the problem is electrical/electronic. When I get the unit out, I will probably start with all the capacitors. Problem could be the circuit board. I believe an updated board is available from Airexcel.

[gfs1943]

I made an appointment with a service facility to let them look at the AC. I brought the coach to the house yesterday, to prepare for the trip to service facility today. I decided to give it one more look myself.

I got the correct documents for my AC model from the Airxcel site. There is an 8-amp fuse inline in the condensor blower high-speed wire. That fuse was blown. I replaced it and everything now works correctly. I cancelled the service appointment this morning.

That fuse is optional, and not shown on all the wiring diagrams, even for my model. Apparently, what happens is that the condensor fan motor has two totally seperate circuits for high and low speeds. When the thermostat set point is one degree lower than ambient, only AC circuit #1 is called for and the condensor fan runs on low speed. When the thermostat set point is two or more degrees below ambient, both cooling circuits #1 & #2 are demanded. The condensor fan low-speed circuit shuts off, there is a brief delay, then the high-speed circuit is activated. Since the fuse was blown, there was no high speed available so the fan just stopped. If the inside ambient temperature dropped to within one degree of the thermostat set point, the high-speed circuit dropped out and low-speed was re-activated. That would make the condensor fan come on again. Strange way to setup a fan, but I guess it was designed to minimize electrical load.

Since I did not have to remove the AC unit from the coach, I'm not changing the squirrel cage blower or bearings. My unit is so quiet, I have to stick my hand under the blower outlet and feel the air moving to know whether it's running.

Thanks to all who replied and helped me with this problem. I hope this info helps someone else with a problem someday.

[codgerbill]

gfs1943,

DO you have a link to the airexcel site for the documents and wiring diagrams?