AC problems

hi, i hope someone can help me... i have a 95 geo metro lsi 1.3. ac was working fine but not now.. as long as car idles the ac blows cold air. but when you start down the road it just blows cool air!i have checked all controls as i thought the outside air might be mixing in with it.also checked the heater core lines to see if hot water was by-passing an that might have been the problem but not. it just started one day on a trip going down the road. hope someone might can give me some idea! thanks .... mike

by chance have you checked the belt for looseness? if not have the amount of freon checked it may be low.

I agree...had the same problem...if the belt is tight, the refrigerant charge is a little low...134a recharge kits are dirt cheap on Ebay right now...I bought 2 of them for 24.00 shipped last week, but I didn't save the link...just search e
Ebay Motors for "134a"....you'll see a bunch of them. I got the 14oz Castrol can with refrigerant, oil & sealant all in one.

Hi, i have checked the belt, it is tight. the coolent is where its suppose to be. the car gets cold while setting still but once you start down the road its just kinda cool. compresser makes a little noise, not much tho. had one incident where freon came out the bottom of the compresser. there is a long tube with a nut coming out of it. anyone know what that is or whats its purpose? hope someone can help, thanks, mike

If everything else checks just a thought. Did you pay close attention to the ambient temp when checking high and low side 134 pressures and use a quality gauge set like Robinair or Mastercool? Also make sure your 134 stock is not contaminated or for example fooled with by prior owner etc. Make sure you use Virgin 134 not rescrubed stuff they sell in car parts stores. Dupont 134 is the only manufacturer I think. Dupont will drop my vent temp to 33 at 80 degree ambient runs 4 degrees cooler because it not used recycled 134.

Classic is you check your pressures for a trip top it off hit the road, temps climb to 90+ and the AC is pitiful when you need it the most. I dont know the Geo AC system as mine is after market SCS Frigette system. But most have high/low pressure switch. At low RPM pressure cools great, when you run constant at high speed or ambient temp increases pressure builds and high end shutoff kicks out the compressor temporarily. Also if you like AC may want to look into a Phoenix oversize condensor. Mine was so so now AC only take 2 mpg off at highway speeds and can eat a ice cream cone crossing death valley.

Check the pressure you might have 2 much R134, at high speed the compressor builds to much pressure and the high pressure switch like somebody said kicks in meaning the compressor cluch is turned off.