[MARKGMC3]

HI GUY'S

getting ready for our trip to NY next week & was testing my AC units.

The hi / lo Fan is the only thing that works on the front ac unit. The compressors do not come on even with

the thermo set @ 60.

All circuit breakers and the 20kw gen are on & the rear AC works fine.

I removed the PCB & only can see two wires on the back of the board that could be replaced.

Thinking of finding a PCB repair shop to check all the components. (looks like all the capacitors are inside

the ac case.) any ideas?

[bikestuff]

It could be that the board has failed....or the caps, or it could be that the compressor is shot. Have you put a clamp on ammeter on the leads that go to the compressor? Any draw at all?

There is a post on here about my experience with a melt down of one of the control boards. you will want to look closely at the connectors that go from the board to the compressor.

Also, the caps are located right behind the board if I remember correctly.

[Richard]

Mark,

First thing to check is put a voltmeter on the output of the board going to the compressor..There is a good schematic on both the cover and in the SCS manual.

Let's go one step at a time, the answer to this question will cut the problem in half. If no voltage, then it's a board or thermostat problem. If voltage, then it's a compressor, capacitor, or connection problem.

Will the 2nd compressor come on if the setpoint is 3 degrees lower than the actual?

Call me if you like, I am happy to help with the SCS units. 817 223 2056

[folivier]

Just to eliminate the obvious, was the aqua hot switch on when the a/c didn't work?

[bikestuff]

Forrest....I would hate to admit how many times this has bitten me!

Richard, we should develop a flow chart for trouble shooting AC problems. Your approach is so much more cogent than mine!

[MARKGMC3]

Forrest....I would hate to admit how many times this has bitten me!  

Richard,  we should develop a flow chart for trouble shooting AC problems.  Your approach is so much more cogent than mine!  

Richard,

Removed the PCB from the rear basement AC unit & installed it in the front AC unit.

Front unit works fine with the rear units PCB.

So it is the PCB that is bad.[attachment=3751][attachment=3752]

Added views of the front & back of PCB.

Looks like one is newer (one working) & u can see the big difference in the runs.

Not sure if attachment are working.

Going to look for someone to compare the boards.

---

Forrest....I would hate to admit how many times this has bitten me!  

Richard,  we should develop a flow chart for trouble shooting AC problems.  Your approach is so much more cogent than mine!  

Richard,

Removed the PCB from the rear basement AC unit & installed it in the front AC unit.

Front unit works fine with the rear units PCB.

So it is the PCB that is bad.[attachment=3751][attachment=3752]

Added views of the front & back of PCB.

Looks like one is newer (one working) & u can see the big difference in the runs.

Not sure if attachment are working.

Going to look for someone to compare the boards.

[Chester Stone]

Mark, your attachments did not come through. I had my control boards rebuild at a very reasonable price. SCS-Victory RV & Truck Climate Control Repair Service. You can Google them for their phone and address.

[Richard]

Mark,

The runs and the connectors for the compressors are the weak link. A couple of us have installed super heavy duty relays externally to carry the current using the original output from the board to trigger the relays. When you get the board checked out, we could walk you through the upgrade. It's killing a fly with a tank but I don't worry about the board any longer.

I know your an astute guy cause I've looked at pics of your work. You can do a quick check on the board yourself by simply using the voltmeter to check continuity from the connector connection for the compressor to the back of relay. It's pretty straight forward looking at the trace (run) on the back of the board. If those traces have continuity, then its likely one or both relays on the board are kaput. But's that's guessing without some diagnostic with the Voltmeter.

[MARKGMC3]

Mark,

The runs and the connectors for the compressors are the weak link. A couple of us have installed super heavy duty relays externally to carry the current using the original output from the board to trigger the relays.   When you get the board checked out, we could walk you through the upgrade.  It's killing a fly with a tank but I don't worry about the board any longer.

I know your an astute guy cause I've looked at pics of your work. You can do a quick check on the board yourself by simply using the voltmeter to check continuity from the connector connection for the compressor to the back of relay. It's pretty straight forward looking at the trace (run) on the back of the board. If those traces have continuity, then its likely one or both relays on the board are kaput. But's that's guessing without some diagnostic with the Voltmeter.

[MARKGMC3]

Richard...
Had the pcb's rebuilt....one was bad. Installed both & they both work.

Left for ny ..now at Rabun gap ga. Rv. Park. Ran both units & after one hour

The front one quick again. Turned it on a few hour later & it worked.

I will try your relay fix. Just noticed a newer Newell in this park ...

Thanks again.