20 Most Recent Friedrich Digital PTAC PDH12K35B Central Air Conditioner Questions & Answers

You have a bad start capasitor

get model and make numbers and google it up you might have luck to find the part for purchase

i think so may be the heating coils are not getting heat without power supply check out the plug in wire and whole supply.

A Power Reset will fix most things. Turn off the power at the breaker for a couple of hours. It resets the main board and all the relays. Service Manuals in the link https://www.google.com/search?q=Friedrich+Model+MR36TQY3JMA+mini+split+blinking+codes ..

bad thermostat.

Press fan and speed together for 3 seconds

Time to get an air conditioning engineer in to service it.

check with a dealer locally that brand is not sold here in usa

check for blockage if ok check for crack

heating switch over or unit failure --circuit or conrtol failure

That's what happens with loose electric connections. Need to go from the breaker to the AC unit power run inspecting each wire splice, all electric connections need to be clean and tight.
A loose connection becomes electrical resistance and electrical resistance consumes power, power consumed is dissipated as heat. Overheated, charred, discolored connections can be cut off and reconnected when found.
Start by tightening the circuit breaker wires, and neutral if any.