Daikin R71FJ7V1 playing up

[Brian_UK]

I have an old, 1996-R22, R71FJ7V1 condensing unit which is shutting down on high pressure protection.

After starting the compressor and condenser fan both run up as expected. After a variable time period the condenser fan stops, no power to it, and the compressor keeps running until it hits the high pressure switch. The fan motor overload does not trip out.

The three sensors for the air intake, pipe and discharge appear to be good on the limited readings that I could take on them.

Took out the PCB, couldn't see any dry joints or overheated components.

So I hard wired the fan to run in HH speed whenever the compressor runs. I haven't measured any gas pressures or temperatures.

I am thinking towards a failing control PCB or maybe the sensors going awry when temperatures change.

Any thoughts people?

[Gingerair]

Hi Brian

Had a similar problem recently, on my unit the condenser fan has 3 speeds, think it was one of the relays on the main pcb that switch the fan speed that had gone toes up.

It shares the same main pcb as a twin fan unit, so could get the condenser fan to run ok in the unused plug, but didn't have time to check whether it cycled ok or eventually faulted or not.
Have ordered new fan motor, capacitor & main board.
Will be interested to see if the unit is still running without fault on my return..

My unit is a RP71L7V1 yr. 2003

Hope this helps..

Ginge

[frank]

I've had quite a few of these as well Brian.

The ambient air sensor plays a big part in controlling the fan speed selection and on occasions, I've had to shove the sensor into the coil fins to keep the fan running.

We've also ended up replacing the outdoor pcb and sensor on a unit in Manchester but then a few weeks later the same problem returned.

Just like you I now tend to hard wire the fan onto the compressor contactor.

I had the same fault on a R100F just 2 weeks ago so that is hard wired now

May have to go back when winter comes around to change the fan speed though

[Peter_1]

I should have given the same advice as Gingerair. The units those days weren't speed controlled but the PCB choose between some speeds.
To be honest, I should have repair it the same way on such an old unit, good chance if you install a new PCB that something else will fail in a short time.

[TRASH101]

Hello Brian

Why not fit an aftermarket low ambient kit or use an old HP switch to cycle the fan?

[Brian_UK]

Lots of suggestions folks, thanks.

Frank, I did try having the sensor on the inside of the coil but it didn't make any difference.

Trash, not a bad idea but may modify along with Frank's thought about the winter period. Perhaps fit a c/o thermostat to switch between fan speeds.

I was back on site today and the area it serves is like a fridge now, told them that they could raise the stat setting but they want the area kept cold.

Why? you might ask; well it is because they have two small meeting rooms were the compressors have failed and when everyone get too hot they spill out into the cold lobby.

There's Councils for you, boyo.