Compressor runs but no fan

[Jayro88]

So here is my situation. About 4 weeks ago I tested my AC and and everything functioned correctly. Now I am getting ready to take it out for the weekend and the AC isn't working properly. The compressor kicks on and runs as it should, but the blower motor doesn't run. (See pics below for reference)

Info on the unit:
Duo-Therm Model 57915.621 with an Easy Start from MicroAir installed. Trailer is a 1994 Classic 300 (AC is as old as the trailer from what I can tell)

What I have done so far:
1. To eliminate thermostat wiring I jumped the wires at the unit. I can hear the relay for the fan click. There is a slight hum, but not a loud buzz or a chatter from the relay that would make me think it is toast.

My thoughts on trouble shooting and what it could be:
1. The capacitor for the blower motor could be out. I haven't opened up the roof top unit yet, but I am hoping to see a swollen capacitor I can replace. However, with the EasyStart installed you remove the "Start" capacitor but leave the run capacitor. I am not sure if the start capacitor is just for the compressor or if it is also used for the blower motor. Since the compressor works still, does this point to this not being the issue. Here are the install instructions for the EasyStart if it is helpful for reference. http://microair.net/main/products/ma...Penguin_II.pdf

2. The fan motor is out. To test this I can use my meter to make sure it is getting voltage when calling for fan. I may also be able to tell if the motor gets hot while trying to run. Do these go out often? There wasn't any signs of it going our last time I used it......no increased noise, slow start etc.

3. It could be the relay in the control box. If the motor isn't getting any voltage, then this is where I would think. I haven't opened up the control box yet, so I don't know if it is a separate replaceable relay or if it is built in to a control board that would need replaced.

Here is the wiring prior to install of the Easy Start.



Anything that I am missing or any other ideas? I guess on the bright side it is only supposed to be in the low to mid 70's this weekend, so having no AC wouldn't be terrible.

[Jayro88]

Good news. It ended up being the capacitor. I was able to spin the fan by hand to get it going. It has started perfectly since then, but I still think I am going to replace it to be safe.

[sundancer 87]

That capacitor is easier to replace and a lot cheaper. If you made it run by spinning it I'd say it's just fine.

[Jayro88]

Originally Posted by sundancer 87

That capacitor is easier to replace and a lot cheaper. If you made it run by spinning it I'd say it's just fine.

It has be running off and on all day today without any issues. My local place won’t have the capacitor I need until Monday, so I am glad it is working. Capacitor is only $20, so that is good. Just kind of a pain to have to troubleshoot and climb on the roof when there were other things to do......and then the alternator belt on my tow vehicle broke. It’s a 3 v-belt system and the alternator belt is the back one. So I have to take off the 2 front ones to replace it.

I swear, if I didn’t have bad luck I would have no luck.

[wahoonc]

Well at least it was a pretty easy fix and you could do it yourself. Just think how happy you would have been having to wait 6 weeks for the shop to get around to doing it, then charging you $300 and then having to probably fix it yourself anyway.

Aaron

[sundancer 87]

Of course the inner belt breaks so you have to dig around until you get to it. Usually one belt breaks and takes the other with it. You'll be replacing them anyway since they'll be off.

Any cap with the same or more capacity will work. Only thing really important is the voltage. Can't go below the rated voltage. HVAC shops have caps that will work if your local shop falls through.