APU and AC trouble

Correct, one would think so.
There is a phone #, email, parts diagrams etc. Contact them if this is the right company. I see heaters but no APU's.
Proheat — Proheat Product Support

 

Yes, I have seen many home mini splits that use that form of restriction. But all refrigerant systems that I am aware of, cautioning that I am not an AC tech, use a dryer in the system as moisture is a vary bad issue. Many dryers use a desiccant medium. Once this medium is saturated, the dryer must be replaced. This is why the general accepted "rule of thumb" is to replace the receiver dryer each time the system is opened.

 

@reeferwrencher

 

Did you read post #11? They also have diagnostic info. May not be able to get parts for it. Maybe they discontinued the APU's.

 

If it frosting up after the dryer(between dryer and evaporator) and it s running in a vacuum it sounds like the dryer is restricted.

 

Note the arrow on the blue drier. Flow is from the condenser into the drier and then out of the drier into the evaporator via the capillary tubes. The capillary tubes control the flow of refrigerant similar to an expansion valve or orifice tube.
"so i'm confused if the drier is the problem or an obstruction in the lines coming out of the evaporator going to the drier." Driers can come apart internally and release dessicant. You won't know until you remove the drier which must be replaced regardless. Should also replace the capillary tubes. Can blow through them once removed. Looks like you are going to have to remove them to connect the drier to the tubes.