AC Issues, Again

[Sparky1]

Krush flew down and spent the week-end with me on the 41, and he was able to charge the AC system which cools great now. Unfortunately, there is still a problem which we weren't able to address given his limited time.

The unit works fine as long as it stays in a cooling mode, as was the case the last time I had the thing charged. However, when temps fall to a sufficient temp to kick off the compressor, it kicks the breaker (small, red reset button) on the wall mounted unit in the master stateroom when the compressor kicks back on. It doesn't do it all the time, but it does most of the time.

In fact, since he left, it has become increasingly difficult to get the compressor to start up at all without kicking this breaker. I have to back off the thermostat to a neutral position, switch to run, the move the thermostat until it activates the compressor. I can pretty much tell when things are going to work or not as I know I'm going to have problems when the fan speed decreases when switching to run mode. The unit will run 5-10 seconds, then the breaker goes.

There is some "Bubba" wiring (wire nuts, butt splices, etc.) on the unit itself in the ER, so maybe it's a voltage thing. I'm just not sure why it would be an intermittent problem as the thing does work properly on occasion. Any input will be greatly appreciated.

 

[Trojan]

It could be your control. Let me tell you what I think is happening and you be the judge. When you first start it after setting it runs fine. It reaches temp and shuts down. When it restarts the breaker pops. But it does not do this all the time. But only after running and never does it when in the heat mode. Is this correct? What control do you have?

BILL

 

[krush]

I can pretty much tell when things are going to work or not as I know I'm going to have problems when the fan speed decreases when switching to run mode.

I thought I noticed that when I was there.

From this I would highly suspect a couple of things: FUBAR wiring causing big voltage drop, messed up start circuit/winding on the compressor, or bad capacitor--or a combination.

Looking at the crap-tacular wiring and considering it starts fine after sitting for many hours, my instinct is the wiring. When you start it from idle after 4+ hours, the wiring is all cool and can handle the inrush. After the thing has been running for some time, the FUBAR wiring may have cause the copper to get warm and it can't handle the amps required as pressure builds on the high-side, thus tripping the breaker.

Get a wiring diagram (one reason I couldn't do much more diagnosing when I was there) and get a meter and start checking for voltage drops in the supply wiring. Check the run voltage when the compressor is running too.

Giving the bubba-tized crap I saw, I would concentrate on the wiring first.

 

[Sparky1]

Hate to mess up your theory krushter, but having it sit all day didn't make any difference when I got home to the boat last night and switched it on. It took about 4-5 tries to get it to kick on.

I can see where the wiring at the unit itself may affect the compressor, but how can it affect the fan speed on just the one unit that has the thermostat?

BTW, I read up in the owner's manual about this system, and it is the original Cruise-Air 12,000 BTU system with one 6,000 unit in the stateroom and another in the salon. Only the stateroom unit has a thermostat (by design) which controls both units.

 

[krush]

I can see where the wiring at the unit itself may affect the compressor, but how can it affect the fan speed on just the one unit that has the thermostat?

Need wiring diagram......

 

[Sparky1]

It could be your control. Let me tell you what I think is happening and you be the judge. When you first start it after setting it runs fine. It reaches temp and shuts down. When it restarts the breaker pops. But it does not do this all the time. But only after running and never does it when in the heat mode. Is this correct? What control do you have?

BILL

Bill, this unit has the old rotary set up with three knobs. As for this happening in the heat mode, I never had it do this while in heat mode. I don't know how that could make any difference as it's just a reverse cycle unit.

It has run for 12+ hours straight this week-end with no problems. It's just the start-up phase for the compressor that causes the problem.

 

[Sparky1]

Need wiring diagram......

Wanna Google one up for the ole' man?

 

[mobilemn1]

Sparky, it sounds like the start capicitor for the compressor is weak. This is for kick starting the compressor motor instantaneouly for the start winding in the compressor to start turning the compressor motor. Once it starts moving the run winding kicks in. This all happens in just a few seconds. If the compressor does not kick in like its suppose to, a big load is put on the wire trying to run the compressor before it reaches speed for the run winding. The wiring will heat up also causing the breaker to pop. Hopfully its just the capacitor, and not preliminary trouble with the start winding.

 

[Sparky1]

Thanks Daryl. I actually talked with Scott aka boatsb about this over the week-end, and he shared the same thoughts. As krush said, I've GOT to come up with a wiring diagram for this system to know what the heck I'm even looking at. Hopefully I can rob one of these off the system that is non-operational (will be looking into that as well), just to see if that's the problem.

 

[Will]

Your breaker itself might be going bad.
Will

 

[Sparky1]

Your breaker itself might be going bad.
Will

That's always a possibility, but given the change in fan speed when kicking on the compressor, I think I'd have to pretty much rule that out.

 

[captddis]

I am sure Jay did not overcharge the unit, but if it cools real well and then trips out in heat I would check charge. They are much more sensitive in heat mode.

 

[Maynard Rupp]

I am thinking overcharged also. Preassures too high will stall the compressor on startup.

 

[krush]

Not an overcharge, and I doubt the start cap too. High side was normal. I couldn't get it to trip out when I had the gauges hooked up....pissed me off. But I never saw any sky-high pressure.

When I heard it trip out, it was after it ran for a good 10-15 seconds. This is beyond the realm of a start cap.

Early in my stay it ran for hours at a time. I don't know what it does now, but I do know what I saw in regards to wiring. I didn't have time to start digging in without a wiring diagram. Also, I didn't want to touch anything and have the wires crumble LOL.

 

[Sparky1]

Now krushter, you're making the old gal sound pretty bad there son. Quite frankly, the wiring is in need of a little tweaking. I'm one that doesn't try to fix things that aren't broken, so before these problems popped up, I never paid any attention to the wiring as I know it was that way when the PO bought it. He was the very meticulous type, but he too wouldn't try and fix something that wasn't broken.

Here's the deal, once I get the compressor through the kicking on stage, the AC runs for as long as it takes for the thermostat to kick in and shut off the compressor. I'm no expert, but I do know an AC system requires and uses more power when the compressor kicks on. Would that not be an indication of a loss of voltage between the main power supply and the AC unit itself or a sign of compressor problems?

I have to share something funny that happened Sunday night while me and the boy were asleep. I heard the AC unit shut down around 4AM, so I got up to switch it over to fan only mode as it was plenty cool, almost cold. Needless to say, I was still half asleep when I made my way over to the unit. About the time I hit the reset button, I saw what appeared to be large flashes of light which resemble electrical arcing. Problem was, it was coming from the floor near the base of the chest of drawers between the beds.

I switched on the lights to see if I could see anything, but I didn't. That in itself made me a bit nervous, and I began to think I was just seeing things or that it was lightning which only looked like it came from the floor. It wasn't until morning that I realized what I had seen. The boy had gone shopping with his mother earlier on Sunday, and he came back with some fancy new tennis shoes with very bright lights all around them. The minute he put on those shoes, I knew I'd found my "problem".

 

[REBrueckner]

A breaker CAN cause such an intermittent issue..if you donlt switch to another, at least flip the one in use on and off a half dozen times and be sure it is in the ON position....so can a loose wire or dirty connection although the symptoms make this less likely....and as far as I know, capacitors either work or they don't...

Sometimes with one person activating the ac start via the control, an observer right at the wiring and compressor might see a flash or arc at start...that would be an indicator or an intermittent problem.....

 

[krush]

Sometimes with one person activating the ac start via the control, an observer right at the wiring and compressor might see a flash or arc at start...that would be an indicator or an intermittent problem.....

I saw an arc on one start.....this is why I'm hellbent on condemning the wiring. Obviously I didn't observe all starts, but once is enough for me.

 

[Sparky1]

The breaker I'm referring to is basically a reset button. It cannot be switched on and off.

 

[Sparky1]

I saw an arc on one start.....this is why I'm hellbent on condemning the wiring.

Contrary to your earlier statement, we did in fact get the breaker to trip while your gauges were attached. Remember?

 

[67hat34c]

Randy I did not read this whole thread but if you are talking about a "reset switch" then you may be talking about the thermal over load switch. Takes heat or a defective switch to trip that.

Can be a number of things but wires is the first to look at.

How is the shore power hook up, does the connector get hot at the pole or on the boat? What about the breaker panel and amp meter? connections good there? ( we had loose wire on amp meter that caused it to burn)

This vintage unit most likely uses a series of relay switches to controll it.
Any of those could be suspect.

You can check volts at the unit and look at meter when it kicks on and then look for voltage drop. ie your meter can read 120v at the unit but it may drop significantly when it starts up and runs.

If all that checks out then connect amp meter on the wire at the unit and see if it is drawing excessive amps. If so could be compressor is ready to go.