I have a 2003 Subaru Forester. It will cool just fine while not moving. It will also cool just fine if I’m coasting down a hill with my foot off the gas. However, on the highway I have intermittent cooling. It cools for 10-15 seconds and then it blows what feels like straight vent for 10-15 seconds. It has a new compressor, receiver/dryer, and expansion valve and is fully charged. Any ideas?
I would suggest that you take it back to the shop that replaced the compressor, receiver/dryer, and expansion valve. Surely there is some type of warranty relating to their work.
The system was probably overcharged.
When this happens, the AC will work fine when idling or coasting because the compressor is spinning at a slower RPM.
But when driving at speed, the compressor RPM’s are faster. This raises the pressures inside the already overcharged system to where the expansion valve freezes going into the evaporator.This then causes the high side pressure to increase to where the high side pressure switch cuts power to the compressor clutch. Then when the pressures equalize within the system, the expansion thaws out, and the cycle starts all over again.
But I agree. Take it back and have the pressures tested for overcharging.
Tester
Another vote for taking it back.