Carrier AC

So, from Chris' explanation, is this correct...? If PTC is used, and PTC is good but Herm/Compressor side of Run Cap is BAD, it'll attempt to start but fail because of the Run Cap? But if PTC is missing or open and Run Cap is GOOD then it'll start and run, just without any start assist?

I wouldn't call it "Wonky". Dometic uses it on their marine rotary compressor air conditioners. It works the same as a start cap and relay. At start up it bridges the run cap and then drops out. It works very well and has for years. I've only replace about two of them in 15 years.

Carrier used a very wonky start circuit- instead of using a separate start capacitor to shift the phase angle, they simply short out the run capacitor with a PTCR.

This is how it is wired:


This is how it looks:

roachcoach wrote:
I am having problems with my front ac . I have 2 ac , one that works great and one that is just troublesome . Am aware that Carrier doesn't make these rv ac anymore . Ok here is my most recent problem , this morning my front ac would start (motor) and then it would shut down when the compressor tried to kick in. Mind you this went on several times. A couple of times when it turned off it would not do anything. I already know that I have to reset everything off then turn it back on which is what I did. BTW the breaker never turns off. I go through this all the time. The ac is working fine at this very moment but it may turn off later and then again it may not turn off for a long time. Hoping somebody can help.
Thanks

It is probably the capacitor. You may even smell burning rubber after several attempts. It is a simple two prong plug on. I think you have to take the cover off outside to get to it. We have the Coleman Mac heat pumps. Perhaps all you have to do is access through the filter opening though.

On Carrier the start capacators are both in the same can (Dual cap).

Try it in FAN mode. if the blower works Good. or bad, depending on your POV.

If it starts to run when the compressor kicks in but, then a few seconds later it stops and ***IF*** the green light flashes like five times (or groups of five) you have a major problem. POSSIBLY loss of coolant, This is a service call.

On teh Carrier Air V there is a spot just off the compressor where two lines dip down in a "U" shape.. Just like a plumbing trap.. This is, in fact, a vibration trap designed to keep the vibration of the compressor from causing problems down stream with cracked joints and such.

Problem is the idiots let the two pipes touch, and they wear each other out and HISS goes all your coolant.. Also it's a hard spot to fix. Replacement may be in order... IF you do replace it I think Coleman, and I know Advent Air, make a drop on upper unit for Carrier ducted non-heat pump models. THis is less expensive than a entire unit.. Save the blower and the cover.. May need 'em some day (I saved the blower, fan, motor that runs them, cover and start capacitor assembly)

I assume you have the crazy wireless remote?

My Compressor usually doesn't start for a few minutes after the fan starts, which is normal-especially if I just changed modes on the system.

I honestly can tell you that the troubleshooting is not too bad if you're capable of using a good multi-meter, if not I wouldn't mess with any of this and plan on replacing the unit. You can still buy Carrier ACs that were overstock units and are perfectly good to go.

Remember- to truly reset the AC you must shut off AC power and pull the 12V fuse-I think it's for at least 30sec?

I'm familiar with Coleman, but I'd still guess that there are several capacitors in a Carrier A/C unit:

1. Fan Run (smallish metal "can")
2. Compressor Run (larger metal "can")
BUT... 1. and 2. might be combined in one larger "can" with terminals marked "Fan" and "Herm" for Hermetically Sealed, the Compressor part)
3. (probably) Compressor Start (very likely a plastic case) and some sort of Start Device, Relay or special Resistor)

Sounds like Fan runs OK and the issue's with Compressor. Some systems have a delay built in, so Fan and Compressor don't start at the same time. That could explain some of the strangeness you're experiencing.

After a few unsuccessful start attempts, the compressor will get hot enough that a thermal safety opens the circuit and it won't try to start again till it cools, which could be 15 minutes, maybe more.

Are your Front and Rear A/C units alike? If so, you could switch the capacitors between them and see if the problem stays with the unit or follows a capacitor.

If you want to try to swap them, open the circuit breakers before you take the plastic cover and the metal shroud around the capacitors. Then before you work on the capacitors, short across the terminals to be sure they're discharged. Draw a wiring diagram and/or take pictures. If you can get pictures, please photo the capacitors, and the wiring diagram if there's one stuck to the shrouding up there. Post'em here.

I would check the start capacitor first.