A/C Freezing Up?

My A/C works fine most of the time, but after driving on the highway for long periods of time (>2 hrs.) the A/C stops blowing cold, and blows weak, even when on the max setting. If I turn the blower and the A/C off for a while then back on, it works fine again.

It seems like something is freezing up as it has much of the same symptoms that a home A/C unit does that freezes up.

I checked the system pressure before summer started with a Wal-Mart kit and it checked out ok.

I don't have much experience with A/C systems, so any input would be appreciated.

Sounds to me like its low on coolant. I would take it to a pro to at least diagnose. Maybe with the "wal-mart kit" it has bee n leaking since you checked it.

Sounds like the evaporator is freezing and blocking air flow if as you say the blower volume is noticeably decreased. Only checking low and high side pressures and proper air flow over the evap will allow you to properly diagnose this.

Only checking low and high side pressures and proper air flow over the evap will allow you to properly diagnose this.

Is this something that can be done at home, or does it require special tools/equipment that only a pro would have?

Thanks for the responses, I will keep you all posted.

It sounds like you have to much freon in the system. You need to use guages to tell. Some times they can be rented from auto parts stores.

My '96 did the same thing. I ended up replacing the compressor cycling switch on the aculmulator or whatever it is called as the compressor was engaged too long