Recently came across a 15 year old Amana split system on a PM check. The following parameters are what I found during the PM:
1. Temp Diff.= 12 deg
2. Suct Press= 48 lbs
3. Head Press= 165 lbs
4. SH= 35 deg
5. SC= 13 deg
6. Outdoor Ambient= 78 deg
7. Return= 67 deg
With the evaporator outlet by indoor coil and suction line warm to touch and filter clean I decided that if unit wasn't low on a charge then system probably had Txv and that could have bad powerhead or internals damaged or maybe even poor bulb location or lack of insulating.
After adding charge to system Suction stayed right @ 48lbs and head continually went up and as expected suct line temp remained warm. After looking found that unit did have Txv and that bulb mounting was @ 10 and 2 and insulated well. I did not warm up bulb to see if I could open valve, looked pretty obvious, bad powerhead or valve.
Told homeowner of situation I came into and because powerhead and valve body could not be seperated a new Txv should be in the works. He agreed and I came back 2 days later with bossman to put new one on.
To boss said initially looked like a great call till after completing Txv changeout he looked and found that A-coil was partially plugged and that this was the culprit. He cleaned before we tested out unit with new Txv. Unit worked great after everything was done.
My question is: who was right? I performed the initial start up suct press went right down to 48 lbs and stayed and suction line was always warm to the touch. SUCTION LINE AT BULB LOCATION ALWAYS WARM. Txv never hunted. He said poor airflow on Txv system usually looks like low charge or refrigerant restriction. Is he right? Do I need to go back to school?
Appreciate feedback, caught hell over this job from owners and management.