A/C doesn't work after a long drive

[lking78]

2001 cobra convertible -- drove it 4.5 hrs yesterday morning getting home after fathers day -- preformed great, top down all the way -- everything nominal -- ran into an isolated shower at home and after i got the top up -- turned on the a/c -- just got hot air -- i had used the a/c a couple of weeks ago and it worked fine so i was surprised -- started it up this morning -- a/c works fine --

so the failure seems to be related to the long drive -- appreciate your thoughts on what is going on --

larry

 

[96blak54]

Could be low on gas, might need a top off. The parts stores sell recharge cans with florescent dyes that will reveal where a leak is. Could be a failing high pressure switch. If you did a sprinted high rpm run while a/c was on, itll cut the pump off briefly.

 

[Miltoid]

If the compressor is running, the only way to track something like this down is to check the pressures with gauges. I bought a good set cheep on the Jungle Prime site. Also make sure the cooling system is up to snuff, clean rad. and condenser fins, no obstructions, cooling fan working etc. A bug screen in front of the evaporator is a no no.

 

[RAU03MACH]

when running dose the air change from front vents to top of dash in defrost vent

 

[lking78]

appreciate all the suggestions -- checked freon level, it's good -- recently emptied the cooling system and filled with fresh 50/50 mix -- still works fine around town -- air comes out according to the dial setting -- doesn't change vents -- i believe we made the same trip last year and used the a/c without an issue -- only difference between then and now is that i changed the transmission to a 6 speed -- so on this trip, much of the time i was running at 2500 rpm or below -- i think 80mph in 6th is between 2000 and 2500 if memory serves -- maybe the compressor doesn't like too long at lower rpm -- but it works now and i can live with that -- thanks again for all the comments and suggestions