P4 ERROR CODE TROUBLESHOOTING:
First what is operation of unit?
Pull disconnect, wait 45 seconds.
Plug back and run system and max temp for either heating or cooling.
There is always a 5 min delay
Once system comes back on, what happens from the moment the unit comes on to when the P4 error occurs?
Any operation of the outdoor system? (Fan or compressor)
From here we do two ways
IF FAN AND COMPRESSOR RUN,
Cut power and test MIN/Max Test.
MIN/MAX :
With power cut, Disconnect UVW (COMPRESSOR WIRES) From the board they attach to.
From here you will switch meter over to DC Volts. And test will go as follows:
Keep meter on 2 connections U or V or W.
Power unit back on, with leads on combination and in DC volts wait for initial signal that is shot into compressor from the points being tested on the MCB. This will come after the 5 min time delay.
From here reset unit as previously done and do again for the second combination. And once more for the final one.
Will be testing all three combinations this way UW / VW / VU
If voltage spike is different and each combination Main control board is bad.
IF checks out. OR IF FROM THE BEGINNING THE FAN NOR COMPRESSOR RUN.
Check the following
Ambient temp surrounding the condenser -
Standing pressure -
Resistance at the compressor head
3 wire coming from compressor. So three combinations, Testing in OHMS. Compressor wires might be different color then shown below.
RED-Blue -
RED- Black -
Black-Blue -
Compressor Leads to Ground -
Testing for continuity here. Checking for the beep between any lead to ground
And finally testing temp sensors.
There will always be three on condenser, you will be testing for resistance.
And you will find all three sensors on Main control board. Usually labelled as T3,T4,T5 OR TP.
Needle point adapters will be needed for this testing.
AND JUST CONFRIM the reading coming of each induvial sensors. and confirm ambient temp at the moment of testing
Ambient temp
t3
t4
t5