AC Compressor running really hot and not cooling

[johnjen50]

Friend of mine has a new boat and the ac compressor in the mid stateroom is running super hot, and just blowing warm air. We checked hoses for obstruction and nothing. We also shut the system down and let it reboot. Why would the compressor be running so hot? Really hot to the touch and you can't leave your hand on it. Not a Hatteras, but a completely new system. Cruiseair. Any thoughts?

[krush]

Can't fully tell you without data (pressure and temps), but it sounds like it's low on refrigerant.

[captainwjm]

Can't fully tell you without data (pressure and temps), but it sounds like it's low on refrigerant.

I agree, but would make double sure that you are getting sufficient cooling water.

[Reefgeorge]

The compressor needs two things to be below its temp max. Proper flow and level of refrigerant vapor into the compressor and proper heat exchange for the liquid high pressure output. Also, the compresor itself has to be working properly of course. There are high pressure and low pressure sensors on most systems so if the system is way out of bounds it should shut down. How is cooling water flow? Is the suction return line cool and sweating at the service port? Shoot the top of the compressor can with an ir gun near the liquid line output. Even when under the limit, the top of the can is pretty hot. To give you an idea, a properly insulated thermocouple measuring the liquid line output a few inches from the compressor can needs to be under 225F which implies a maximum at the internal output valve max of 300F. Those are high temps and definitely not hand on top of the can friendly. A properly running Cruisair system is usually lower than this but can be quite hot.

As stated above, the complete picture and diagnosis required some gauges and pressures,

George

[Boatsb]

Remember the compressors are cooled with the refrigerant.

Check for the following

1) cooling water flow. I have seen new installs with one piece units have issues with cooling water.
2) return gas (larger line) cooler than high pressure .
3) inlet air to outlet air temp.

[johnjen50]

Thanks all. We popped off the inlet and outlet water lines and there was no obstructions. There are two other compressors that are running as well and neither are anywhere as hot as the one in question. They all operate off the same seawater pump, so water flow should be ok. Matter of fact this compressor is betwen the two others that are working fine in the raw water line. Thanks again. I think we will have to check refrigerant pressure.

[Reefgeorge]

Don't rule out sea water flow as the circuit may not literally be in series.

No doubt gauges are best. High, high pressure readings would help you with sea water flow determination. I clean the circuit when the readings start to climb during a routine check. Garden hose only, high pressure pulses, each circuit isolated. Never used acid and pressures are factory new after 15 years. Low charge would of course also be obvious.

George

[Pascal]

Remote condensers or self contained ??

Multi compressor systems are never in series or you d send increasingly hot water down the next compressor.

Don't assume that because two condensers get enough water that the third does. I ve had this happen... three units with good flow but some shells clogging the fourth. Pull the outlet hose, put it in a bucket and check flow

Otherwise you need to check pressure. Too low and you may not have enough gas to keep it cool... too high and the compressor could be struggling

[racclarkson@gmail.com]

Times I wasn't getting cooling water to Cruiseairs the units (multiple) shutdown showing high pressure fault on display. (Did I mention my experience with March Pumps?) Everytime I've had one hot as a firecracker they've been out of gas.

[Finalee]

Get some gauge readings. Sounds low on gas but why guess.

[krush]

Times I wasn't getting cooling water to Cruiseairs the units (multiple) shutdown showing high pressure fault on display. (Did I mention my experience with March Pumps?) Everytime I've had one hot as a firecracker they've been out of gas.

Agree with ya, which is why I said low on the gas. If condenser cooling was an issue, it would hopefully be shutting down due to excessive pressure on the high-side.

[rustybucket]

I'm still learning refrigeration, and agree with all others on the things to check. Question I have: Would a bad run capacitor cause the compressor to run hot by drawing a higher than normal amperage?

The unit would probably still cool though, so that might rule out the run capacitor.

Would be a real easy thing to test by swapping a run capacitor from a known good unit.

My vote, with the given info, would be for a freon leak and hence a low freon condition. Find out if the freon is indeed low, then find/fix the leak before recharging.

[Pascal]

Either low or high press would trip the safety switches once it reaches a set level but I ve had either condition cause the compressor to run hot when not bad enough to trip switches

Need to get press readings

[Mike36c]

What I've found helpful on my systems that share a pump is to install a pvc valve on the outlet side of each unit's raw water loop then tweak the flows to balance out everything. Once installed you could divert all the water to the one unit to help diagnostics.

[johnjen50]

Great help thanks. No tripped switches and no fault alarms. He is having a refridge guys come and take a look at it. He will test the pressure, but finding a leak could be painful as we looked at the air handler lines and didn't notice any. Neither on the compressor unit. Thanks again. Ok let everyone know what the verdict is.

[racclarkson@gmail.com]

Great help thanks. No tripped switches and no fault alarms. He is having a refridge guys come and take a look at it. He will test the pressure, but finding a leak could be painful as we looked at the air handler lines and didn't notice any. Neither on the compressor unit. Thanks again. Ok let everyone know what the verdict is.Maybe not. If it quit suddenly, the leak will likely show itself to a pro in short order. It's the slow leakers that are a B%$#@&!

[rustybucket]

Maybe not. If it quit suddenly, the leak will likely show itself to a pro in short order. It's the slow leakers that are a B%$#@&!

No kidding about that!! A guy I was talking with the other day was saying you can put a UV dye in the system and use a blacklight, anybody here know anything about that?

[Pascal]

I ve had a few leaks over the years either on my boat or boats I was running and the guys use a sniffer to trace the leaks. Pretty quickly quick job usually

[racclarkson@gmail.com]

I ve had a few leaks over the years either on my boat or boats I was running and the guys use a sniffer to trace the leaks. Pretty quickly quick job usuallyIn my cases, the sniffers generally sniff out leaks in the evaporator. Not a good spot.

[krush]

Grabbing your pipe is a good way to diagnose stuff quickly before digging too deep, if one understand the theory.

Feel line returning to compressor close to compressor. Should be cool
Line leaving compressor will be hot (careful).

Line leaving condenser should be subcooled liquid and cool (cold sea water) or warm. It should not be hot. If it is hot, most likely cause is poor cooling water.

Pressure gauges combined with temp readings tell a lot to somebody that knows what they are looking at. But they aren't very useful to somebody that is clueless.