Carrier A/C Compressor making a humming noise

If fan is slinging water or rust dirt it'll male noise.

EDIT: Come to think of it, some window units directed condensate to a recess in the outdoor fan shroud. The fan then slung the water onto the condenser coils. This made the condenser more effective AND kept water from running out of the unit.

PTC is the most basic of start assist "disconnect." It's like cranking your car while you count to Three. Then let go of the key whether engine started or not.

If you saw a cylindrical plastic capacitor your A/C has start assist.

Will download the manual later and have a look.

So I was able to locate the service manual online for my unit.

http://www.transportaircon.carrier.com/Files/Bus/Local/US-en/T298.pdf

It details how to discharge the capacitor. It also mentioned a PTC:

Positive Temperature Coefficient Thermistor
(PTC) (Start Thermistor)

It doesn't show what it looks like but I recall seeing a little black canister in the control box with the capacitor. If it is, I guess I have to test and/or replace that too.

Since Carrier no longer makes or service these units I will post post the Owner Manual and Service manual for others. I will do it in a separate thread.

I did look at the capacitor. There is only one that i saw which shows on the diagram in the manual.

I will take pictures to get the specs to get a replacement. PPL is hear in Houston so I will get the capacitor and see what happen. It is easy to access and replace. Long shot but cheap compared to a/c replacement.

I saw other post about discharging the capacitor so I will consult my neighbor.

I will post results

While you were up there, did you get pix of the Capacitors and the Wiring Diagram?

An A/C may have

As few as ONE,
Probably TWO, and
Likely THREE,

Capacitors.

Only a Compressor Run Capacitor
Compressor Run and Fan Run Capacitor (could be individual or a combined unit)
Two Run Capacitors plus a Start Assist

Start Assist is a Capacitor plus a device to get it OUT of circuit once the Compressor starts. Think of that as the starter in a car. The Key has to be released, from Start to Run when the engine starts. Compressors with Start Assist have to get that component off line to get into RUN mode.

I'd like to see Diagram AND a Pic of the actual capacitors because Start Assist can be an option that's shown on every Diagram but not installed in every Unit. You also need to get the specs from the Capacitor(s) if you plan to replace one. We've had enough capacitor trouble with out home A/C that I keep spares at the house. I also have spares and spare start assist for the RV A/C, based on the issues at home and several OP's here mentioning failures in their RV's.

You can replace a Combined Compressor + Fan RUN capacitor with two individual ones, replace two individuals with a Combined, use only one side of a Combined, etc. The capacitance (40-MFD as an example) and voltage (probably 440, maybe 370 and you can replace a 370 with a 440) are the two specs you need to match in replacement capacitors.

Your neighbor can explain safety in working with electrical components, and capacitors in specific.

My neighbor came by but he was not very much familiar with RV air conditioners. He used his wrap around gauge to measure flow to the compressor. He said the electrical flow was good and perhaps the bearing are bad in the compressor.

I've re-read the feedback provided and I'm leaning toward testing/and replacing the capacitor but it appears that it's function is starting the compressor as oppose to running it.

Thoughts?


Here is the manual for my ac. It contain the wiring diagram and other info. I have the Standard Unit

http://www.transportaircon.carrier.com/Files/AirV/Local/US-en/customer_service/99-00469-00.pdf

Funny you mentioned leak from rust. While looking at the unit, I noticed that water is accummalating at the rear of the unit where the fan turns. I don't see a drain but will look closer and drill a small hole to allow drainage if a drain port doesn't exist.

At any rate, while the compressor is on, I noticed what look like bubbles from the pool or water. I attributed it to the fan turning becuase the pool is at the base of the fan blade. I neglected to turn off the compressor and see if the bubbles still appeared. I'm going to do that before he comes to see if I have leak in the system. That may save him some troubleshoot time.

I suspect if there is a leak it wouldn't be cooling and the freon would have leak during a single use. I noticed the noise a few trips back.

I will report out the results

Even better! Please let us know the process used and the results found.

Be surprised if he says "compressor" but ya never know. Central systems have service ports where a tech can attach gauges, but "room" units, home fridges, etc. do not. They're sealed upon assembly with a "lifetime charge." Which is about true. Barring damage or rust/corrosion, there's little chance for the charge to get away. There are "Saddle Valves" sometimes called "Bullet Valves" but experience usually show they create leak points.

Commendable you want to quiet that A/C even though it may be working.

Thanks again for the feedback.

I have a neighbor who is a a/c guy. He going to come by this evening to check it out.

Excellent feedback on troubleshooting. Thank you so much. I do have meter from Harbor Freight as well.

I will post picks as requested.