My kids just bought a house with a Lennox 4 ton heat pump . With our record heat wave, 110 today, the outside unit keeps shutting down. The compressor and fan go off at the same time. It’s a thermal protection device, I’m sure, shutting down the entire unit. After we cooled it down, it starts right up. The problem is, the fan turns the opposite direction from what I’ve ever seen. It pulls the air in from the top and blows it out the bottom. I’ve never seen that before. It’s the original fan motor so there is no purple and yellow wires to switch the rotation. Maybe this is a Lennox thing?

When mine did that, I was told to replace the motor and the cap by an HVAC friend, and that fixed the issue. I'm not saying that's your problem, just chiming in. Cannot remember what mine is, its not a Lennox though.

On a single purpose air conditioer, since “hot air rises” there is advantage to pulling air in the lower sides and blowing upwatd.
Note the more subtle effect that the heat of the fan motor goes up without ever passing through the condenser fins.

However in winter heat pump mode, the outdoor unit becomes the evaporator.
Waste heat from the fan motor would now be a slight advantage if it passed through the coils of an evaporator and added to total heat getting inside the house.
Coil icing of the outdoor unit becomes a problem too, and air direction should “blow downhill” to keep chilled dew from turning to ice between fins.

Cleaning aluminum fins may help. Use the specialized AC detergents.

Box fans set on the sides of the unit “sucking out” could increase total cubic feet per minute and keep the thermal protection from opening the electrical circuit.

A canopy or tarp to block the sun’s rays may help.

A mist of distilled water during the hottest part of the day can do alot,
but tap water contains minerals that will build up on the fins quickly.

The voltage the power company is supplying may be abnormally low too,
which increases current and trips out thermal protection sooner.

Usually when a condenser fan runs backward. The first thing to try is a new run capacitor.
Most likely it will be a dual capacitor. One side for the compressor. The other side for the
outdoor fan.

FYI, I glad to see that 360view above said that "hot air rises" and not the common term "heat rises"
Hot air rises due to the fact that it is less dense or lighter that cold air.
Heat travels from a great amount to a lesser amount which can be up, down, left or right.

Coils may be dirty or it could be low on refrigerant. Both will cause unit to overheat. Turn off unit and try totally flushing coils with a water hose. Unlike a regular air unit a heat pump runs 1 way for heat and the opposite for air so it may be running in right direction.

Blow out the condensation drain line!

Heat pumps have a refrigerant reversing valve to control whether or not the unit is in heating mode or cooling mode. The fan and compressor do not change rotation direction.

Have you checked to see if the A coil inside the house is icing?

Well, I just kept at it and finally found the issue. My very experienced counter guy at the hvac supply house had never hear of this and neither had Another friend that has does ac work for years. This was a dual capacitor 70/10 that checked perfect. The next house next door built at the same time in 2017 with the exact same unit, had all the exact original components and the fan ran the correct way and blows the air up. We cleaned the coils and the motor was labeled with CCW rotation but stil ran clockwise. That is when I noticed that the wires on the capacitor was wrong. The common wire from the compressor was swapped with the herm term on the capacitor. I’m surprised it has run this long. No wonder the compressor was getting hot and shutting down. Sure enough, we googled “Lennox fan running backward” and came up with a guy in the exact same situation. Old Dave must have made several mistakes at the factory! Lol. Now it’s got clean coils and might survive the 110 degree days for the next few weeks. Man this heat is really making my attitude bad.

Great !

It is wonderful to have an identical unit so close by.

While everything is fresh in your mind,
take pictures,
and track down all available manuals and parts lists

If this is a R22 unit
familiarize yourself with the new laws about solely “reclaimed R22”
and develop a plan for future maintenance.

My Lennox unit crapped out the day before leaving for Carlisle. I called the original installer (1994) and they were not available so I called a Mopar friend who works in the industry. He checked it and it was totally out of freon! R22 unit and said that the Gubmint rules state that if it is 25% or less then they cannot refill it, so a new unit was installed when I was at the show. $3800 later for a 2 ton unit and everything is fine... BTW, R22 is $200/lb now!

Keep an eye on the price of r134A, it's already launched, not sure of the final destination though

Seems to be the same scam they pulled with the R12
Hey it worked last time and my bank balance / stock price is tanking so let's do it again

Thanks good info.

I don't have any R22 units left but I do have about 20 lbs of R22 left...........

I bought a jug of R410A in 2018. $90 some dollars. Bought one last week $460.

I hoard Mopar parts AND r22. I’ll be good for awhile. This was a 410 unit. I have not checked that price in awhile.

I don't have any R22 but I've got 30# of R12.