My daughter's prius has started blowing cold air only if the mph is 50-60mph? I've replaced the compressor and recharged it at the beginning of last summer and it has worked well up to this point. Ideas what to check first? I had this happen on a newer VW and it was related to the throttle body not being indexed - apparently the ecu couldn't determine the location of the throttle so it would not allow the compressor to come on below 2400rpms.
definitely worth checking the voltage... from what i understand, thats a decent assumption to anything odd on a prius.
Usually means the condensor fan(s) aren't working or the system is in very poor operating condition. GOOD LUCK!
My guess would be the condenser/radiator is clogged with junk and not allowing air to pass through. Use high-pressure air to blow out the crud. ALSO, how about the cabin air filter behind the glove box?
There's also a pretty classic explanation where the electric condenser fans aren't working. At highway speeds, there's natural airflow through the condenser. At lower speeds, if the fans aren't running, there isn't. Another variation on that is where electrical connections got jacked around somehow and the fans are trying to blow forward.