Troubleshoot Dometic thermostat heat will not come on until u push it to 90 but it never gets that hot

SOURCE: I need to find a cycling thermostat for a Dometic Roof top unit

I ran across the same problem and found the kit to expensive. I gutted the parts added a transformer, contactor and thermostat. Unit worked great and cost about half the price.

SOURCE: Rooftop RV Air Conditioner: temp outside 90 or above. compressor kicks off ....

It sounds like maybe an overload for the compressor is tripping and resetting once the compressor cools. Possibly due to a low charge.

SOURCE: CAR CONTINUES TOO RUN HOT

Try this.

With the engine cool remove the radiator cap. Now start the engine and let it warm up to the point where the thermostat opens. You can usually tell when this happens by checking the temperature of the upper radiator hose, and the coolant level in the radiator. It will start getting a lot hotter quickly when it does and the coolant level should drop.

While the engine is warming up, watch the coolant in the radiator for air bubbles. Fill up the radiator as needed while continuing to watch the coolant level. Having the radiator cap off while doing this allows the trapped air to escape more easily. If you do have a large air blockage then when the thermostat opens you should see a large drop in the coolant level. You want to keep the Radiator full. Once the air bubbles seem to have stopped you can replace the radiator cap.

You may have to repeat the process a couple times if there is a large amount of air trapped in multiple pockets.

A cracked head or block you can usually diagnose as there will be a lot of small bubbles coming out constantly while the engine is warming up, and even more bubbles if you rev the engine higher as the compressed air/fuel will be forced into the cooling system.