AC freezing up

[Joe Duffiney]

Idleing its fine but get on the highway and after a few minutes little if no air out of the dash. Stop and open hood lines frosted. I'm thinkin either low or high pressure switch. If so can they be changed without discharging?

[madmatt]

it's probably either a low pressure switch or a low charge condition. either way the system will need evacuated and the correct amount of 134 measured back in.

[Joe Duffiney]

Thanks I was thinking low pressure switch. I don't think its a low charge because its not cycling on and off.

[More Power]

I'm told that 5% or more air in the system can also cause evaporator core icing. As Madmatt suggested, an evacuation and re-charge should fix it.

Jim

[Joe Duffiney]

That must have been it !! When evacuating I heard the low pressure switch click so I figured it was still working. I wasn't sure how to check high pressure switch so I vacumed down and charged up. It's been 8 days so far so good.