Carrier A/C wont COOL

[FloridaCliff]

I have two 13,500 BTU ducted Carrier a/c's.

Both units have the remote control function.

Problem:

Came home last night and the front unit, which I leave on at 90 degrees, would not cool when I set the temp down to 78.

The fan would come on, it was set to auto, but the compressor would not start.

The back unit worked fine as soon as I turned it on.

Fix:

Since we had our share of lightning I thought maybe the start capacitor had took a hit.

Removed the cover and it tested and appeared OK.

Decided that since the back unit worked that I would swap and test while I was up on top of the bus anyway.

No change.

Noticed on the schematic something named OLP, no drawing, just in the line to compressor.

Found out it is Over Load Protection(FUSE), Removed inside cover, Tested, Good, But voltage was at 9.1 Vdc. 

Hmmmmmm! OK, but other unit is running fine.  Lets check the Vanner out.

Sure enough 9.1 Vdc on the 12 Vdc feed. checked my batteries on input to Vanner 21 Vdc.

Reset charger and voltage up to 27.8, Vanner at 12Vdc, A/C starts and runs fine.

One of the a/c's control boards is more sensitive to the voltage than the others...

Now up to the roof to put BOTH back together.

I believe there is probably a bad battery in my bank of eight house batteries.

But I am done today.

Wanted to share this and save someone else the run around.

Cliff

[buswarrior]

Excellent report!

It's always the %#%$&^ simple things that screw us smart guys up, eh?

happy coaching!
buswarrior

[DrivingMissLazy]

It certainly is refreshing to see someone come on here who has already done the troubleshooting and determined the cause as opposed to some who come on and state something like "my A/C doesn't work, what is wrong?
Richard

[kyle4501]

. . . . .I believe there is probably a bad battery in my bank of eight house batteries. . . .
Cliff

Looks like you're getting your moneys worth out of those junk batteries      


Bring your VOM to the non-rally so you can present the seminar on how to trouble shoot roof airs!

[TomC]

Boy I sure love my old fashioned twist controls on the hang down diffuser-no electronics to worry about there.  Good Luck, TomC

[NewbeeMC9]

Swap test is an advantage to redundancy.

Had to do it one time when the rear air was tryng to start then woud trip the breaker,  swapped the starting capacitor wired to comppressor to the front one and it tripped the breaker and the rear one ran.  

Seem like the new one cost a whopping 4 or 5 bucks.

[Nick Badame Refrig/ACC]

Geeezzze....Cliff,

You didn't even give me a chance!   What goes here?

Need a job?  lol

Nick-