Dometic AC 15,000 BTU

[Charlie_D_]

When running my compressor will drop off and immediately restart. Happens randomly and inside or outside temps do not seem to matter

Thermostat is Dometic digital set on AU. Fan motor continues to run. Fan speed does not change. On start up fans runs a few seconds and then compressor comes on. When temps satisfied compressor shuts off, fans runs about 5 seconds and then shuts off. Has 2 capacitors, neither show signs of leakage. 50 amp unit running on 30 amp cords and voltage when running is 118. Does not fluctuate.

Any ideas?

[dougrainer]

The FAN capacitor stays in the loop while the fan is running. The Compressor capacitor just "jump" starts the compressor then kicks out. Doug

[Charlie_D_]

Spent time in there today for a short period. Did not cycle. Hopefully going on a short trip soon where I can spend more time checking it out.

I ran the AC with fan on high to get a sense of noise. Then low and then back to AU. The fan runs at the same sound and I assume RPM as low. I will be listening for fan changes and air flow when I check again.

Question for Doug. Two capacitors. I assume one is for compressor and the other for fan? I assume they are for staring. If so, do they play a role when running?

[phillyg]

Yea, I've been trying to listen closely when it pauses, but I haven't heard the fan speed change yet. It definitely makes sense to my NON-tech mind as I
recall it's not good for compressors to be restarted quickly.

[Charlie_D_]

Haven't forgotten my post. I am trying to get enough time to go over the sequence again.
Doug I know that a compressor should not stop and start suddenly because it needs time to equalize to prevent damage to the compressor. The reason I said compressor was because there is a "thunk" and then instantly something starts again. I have a voltage meter plugged in to a receptacle and spent some time yesterday listening and when it happens there is no drop in voltage although the needle fluctuates 1-2 V. constantly.
I will try to verify that it is not the fan. Barttletj says the fan shifts speed but I did not notice that.

[bartlettj]

It is normal for Dometic units to stop and restart the fan when it shifts speeds. They run on high when they are more than a couple of degrees away from the set point, then switch to low when it gets close to the set temperature. Next time you run it, see if the air flow stops when it happens.

[dougrainer]

phillyg wrote:

dougrainer wrote:

phillyg wrote:
As far as I know it's normal for the newer units. Both of mine do it.

The Compressor should NOT stop and then restart in a few seconds. Doug

Perhaps what I'm hearing is the fan stopping rather than the compressor, although I'm fairly sure the tech listened and told me it was the compressor and it was normal.

Well, I AM a Tech and I am telling you it is NOT normal:B See my response above about compressor short cycling problems. Doug

[phillyg]

dougrainer wrote:

phillyg wrote:
As far as I know it's normal for the newer units. Both of mine do it.

The Compressor should NOT stop and then restart in a few seconds. Doug

Perhaps what I'm hearing is the fan stopping rather than the compressor, although I'm fairly sure the tech listened and told me it was the compressor and it was normal.

[dougrainer]

phillyg wrote:
As far as I know it's normal for the newer units. Both of mine do it.

The Compressor should NOT stop and then restart in a few seconds. Doug

[dougrainer]

I would bypass the Freeze Thermister. Then see if it happens. One part of your description does not make sense. IF the compressor turns OFF and then attempts to restart in less than 30 seconds----
1. It should not do it as the time delay should kick in
2. The Compressor LOAD would cause the 120 power to drop out or you would hear the system lug down from attempting to restart in a short time without the compressor equalizing. Doug

[Charlie_D_]

Does not ice up. Filters clean. Cools well and compressor only drops off for 1-2 seconds. One of the features,disadvantages, of this unit is there is drop down lights mounted on a decorative wooden fixture that covers what would normally be the exposed part of the unit. Difficult to remove because it is over the island. Bling for the women but not something that attracts the men.

[phillyg]

As far as I know it's normal for the newer units. Both of mine do it.

[YC_1]

Is it freezing up? Take the filter off the inside and look at the little radiator looking thing.