Help...A/C Problem

Could be freezing up then thawing out, back and forth. Have you had any recent AC work done?

 

Turn off your heater hose valves and see if this stops it. Could be air mixture door problems. Could also be low on refrigerant, causing the compressor to cycle off when the suction pressure drops too low.

 

Changing every 10-15 seconds does sound like a blend door control problem.

 

Or its simply a little low on freon. Is the AC compressor kicking in and out every few seconds?

 

The compressor will cycle if the system gets too cold and freezes up the evaporator but the fan should still be blowing fairly cold air till the compressor starts up again. One sure way to see if the system is full of 134a is to touch the high pressure a/c line that leads from the compressor to the condesor that is in front of the radiator. The temperature of the 134a increases as pressure increases so this line should be hot to the touch. Hot enough that you want to be careful when you touch it with the a/c running. When this line gets hot the pressure in the system rises so the condensor or radiator fan comes on to cool the a/c condensor down. It is controlled by the ecm so that it doesn't come on past 40-45 mph, (the fan can't help at this speed). If the line is not hot you are low on 134a so you have a leak, a clog or a weak compressor, (it's barely ever the weak compressor, and clogs generally make the line even hotter). If the line is hot and the compressor keeps shutting off with the fan not running then it is overpressurizing and you will need to look into this quickly. I hope this helps. By the way I'm a Porsche tech not an International tech but being from Florida I have repaired over 75,000 a/c systems and using your hands to feel the temperature of the lines is the fastest way to diagnose. I hope this helps. Joe

 

Your blend door is still faulty. They warp and become miss shaped over the course of time and allow heat from the heater core to leak through. Not really a big deal until it becomes stuck. Shutting off the taps in the Summer time may be all you have to do, but just be aware that door might cause problems down the road.