On our bedroom AC unit when you first turn it on, you can hear it click and the fan starts, then it seems like it lugs down trying to start the compressor. It will then run for about 3 mins and then makes a very loud noise. I took the top cover off and cleaned all around, even brushing the fins with a tool. Had my wife turn it on with me on the roof and the noise is clearly coming from the compressor. I read something about a "kick-start" or "hot start" option for compressors and I wanted to get your opinions. I'm on the house hookup with a dedicated circuit and surge/drop protector, power is not the issue. It happens at 72 or 95 degrees outside. Yes it's out of warranty by a few months. Thanks in advance for reading all the way through.

I would call a regular AC tech and have them check it out.Jerry Parr

Typical roof airs do not have service ports. In my experience problems with the compressor or refrigerant loop generally find you replacing the roof air rather than repairing. I have seen some handy folks add service ports and repair refrigerant leaks and recharge with good success. Not a task for us mere mortals. :)Good luck.

I'd check the start capacitor. It would be round in a black plastic can maybe 3 or 4 inches high and about 1-1/2 or so around. If it shows any sign of something coming out of it, it's bad and needs to be replaced along with the start relay that controls it. Some use solid state devices these days instead of relays. Replace the capacitor and it at the same time. The start capacitor is only meant to be in use less than one second to get the compressor started and then must be disconnected to wait for another start. If the relay fails to disconnect the start capacity as it should, the capacitor will quickly overheat and be ruined. The compressor's start windings could be ruined at the same time so don't keep trying it. The capacitors are a lot cheaper than replacing the whole unit if the compressor burns up.

They do not install start kits any more, just install one and odds are it will be fine.

Dometic AC compressor | Good Sam Community

larry_cad
Explorer II
Jul 25, 2019
dougrainer wrote:
larry cad wrote:
LittleBill wrote:
I love how 6 people recommended hard start kits...

how exactly does this fix the problem of it running fine then in 3 minutes a loud bang?

the unit obviously has issues.

Guess I missed the part about a "loud bang". Just went back to the OP and guess what? I missed it again. Maybe you can point out to me where it is??? Or maybe you can point out to the six of us where it is?

He stated loud noise, not a loud Bang. Noise===bang same thing:h Doug

Doug, you are correct, the OP stated "loud noise", is this post it was translated to loud bang. Subtle difference but significant.
dougrainer
Nomad
Jul 25, 2019
larry cad wrote:
LittleBill wrote:
I love how 6 people recommended hard start kits...

how exactly does this fix the problem of it running fine then in 3 minutes a loud bang?

the unit obviously has issues.

Guess I missed the part about a "loud bang". Just went back to the OP and guess what? I missed it again. Maybe you can point out to me where it is??? Or maybe you can point out to the six of us where it is?

He stated loud noise, not a loud Bang. Noise===bang same thing:h Doug
larry_cad
Explorer II
Jul 25, 2019
LittleBill wrote:
I love how 6 people recommended hard start kits...

how exactly does this fix the problem of it running fine then in 3 minutes a loud bang?

the unit obviously has issues.

Guess I missed the part about a "loud bang". Just went back to the OP and guess what? I missed it again. Maybe you can point out to me where it is??? Or maybe you can point out to the six of us where it is?
DFord
Explorer
Jul 24, 2019
Be sure to remove the old start kit components before installing the replacement parts or else that will cause more problems.
powellmj
Explorer II
Jul 24, 2019
Really appreciate the quick replies and it seems the pricing on the hard starts units are not too bad; so I'll give that a try. Thanks again and I'll update sometime this coming weekend.
LittleBill
Explorer
Jul 23, 2019
I love how 6 people recommended hard start kits...

how exactly does this fix the problem of it running fine then in 3 minutes a loud bang?

the unit obviously has issues.
dougrainer
Nomad
Jul 23, 2019
Learjet wrote:
my bedroom dometic came with a hard start kit in it from the factory...not sure about the other unit...I need to check it out next time.

If you are talking about the small PTCR device in the pic. That is technically a Hard Start device. BUT, it only can be used once in a few minutes. It MUST cool down after the initial start. So, if you have a compressor that starts and then shuts down within a few minutes, that PTCR will NOT be utilized for the restart of a short cycling compressor. Once the PTCR cools down, it WILL initiate a boost for the Capacitor. So, that PTCR is not a good true Hard Start component. You really need a true Hard Start Capacitor kit for best results. But, better than nothing. Doug
Jennifer_Koper
Explorer
Jul 23, 2019
i'am also looking for a highly technical team or concern of AC regarding issue for my home in nearest @ Los Angeles.

it will be appreciated if anyone could advise me / please share with me your experienced if you faced suck kind o problem earlier.
PNW_Steve
Explorer
Jul 23, 2019
If I understood the original post the a/c worked previously and then stopped. If that is the case, a hard start kit would be unlikely to resolve the problem.

A failed start cap is definitely worth looking into.
Learjet
Explorer
Jul 23, 2019
my bedroom dometic came with a hard start kit in it from the factory...not sure about the other unit...I need to check it out next time.

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