High Pressure Shut Down

unloader valve gone

If you are talking about the condensor that sits outside,there are high pressure and low pressure devices that have a red button on the top of them, turn off power and push the button. They are sometines located inside the unit under the fan. Generally there are none and the unit has internal overloads that kick it out. they reset themselves after the compressor cools down. If it resets after cooling down then ask yourself why it got hot. use a hose and clean the coils around the unit.sometimes helps. make sure fan is running on the condensor outside. It should come on first.

thermostat, outside unit bad contactor. inside unit fan relay.

it sounds like the pressure switch needs replacing as this unloads the machine from the check valve up to the heads if pressure present when trying to restart it will cause it to trip when machine stops should get air leaking from under pressure switch for 1-2 seconds then it will stop

Someone will need to find out if the compressor clutch is failing, or if it is loosing power due to a pressure switch or other problem.
A faulty relay or switch could get hot and switch off power to the compressor.

way too high.

This is most likely due to ahigh pressure condition , are the outside coils clean> if not you can wah or vacume them out be carful to shut the power down if you wach the coils. and try not ot get the whole unit wet. wash it against the way the air blow out of the condenser, are you certain its the pressure switch that your resting.. ?

The unit is kicking on and off by a pressure switch. More than likely low pressure which means you may need refrigerant. If it is kicking off on high pressure, it may mean your outdoor coil (looks like a radiator) is stopped up with dirt, grass, etc.

Hi, there is no reset button for your high pressure switch. You need to see if you have lost power to the unit. Check the circuit breaker. By the unit, you will have a electrical box, disconnect. Raise the cover and pull the plug. You should have 2- fuses there, most do. If you can't see any go one step further by removing the plastic cover and see if they are in there. If so, try replacing both fuses. This is where you need to start. You will have high voltage to the unit such as 208/230 and control voltage from the stat and indoor unit of 24 volts. Find out and make sure you have high voltage first and let me know. Use my user name below, and get back to me, we may have to go into it more.
Sincerely,
Shastalaker7
A/C, Heating, & Refrigeration Contractor

Hi, sounds as though you may have several problems, or I should say there are several things that will cause a unit to short cycle and then shut down. First of all, the head pressure in the system if it is getting to high, will cause this unit to shut off on its high pressure switch. When it shuts off the pressure will drop and the switch will reset on auto and start again just to do the same again. Shut the power off to this unit. Take a water hose and give the coil that surrounds the condenser a good washing out. Be careful not to bend the fins down on it as this will prevent air from being released to the outside air. Use a nozzle and adjust it as needed. If the problem was a head pressure problem, this will stop it from short cycling. If I were on site with my manifold gauges, I would no right away if it was a head pressure problem. After doing this, if it starts to do the same thing again, being low on freon will also cause a system to short cycle. If it was fine 2 days ago, I doubt if it is low on charge. Make sure the outdoor fan is up and running as this will cause it to go off on high pressure cut-out. This does sound like your problem. What happens is the coil gets dirty over time and the air can't be removed properly. The compressor will start and the pressures will rise very fast and shut of with in a few seconds. After a few attempts to run, the compressor will lock out on internal overload until it cools off and resets its self. It may take 5 to 30 minutes for it to start and try again. Do the cleaning process I have asked not getting water directly into the electrical control panel, but give this coil a good washing. If this system has a return air filter somewhere, make sure it is clean. Do this and get back to me and let me no if this solved or helped at all. If not, we can go from there. Just look me up with my user name. I do believe its just a plugged condenser coil. The symptoms are as you describe to me. Please get back to me.
I hope the best to you,
Shastalaker7