As the title says - clutch for the air is cycling (on/off) every 3 seconds at idle and the vent temperature will vary with cold/cool flow of air. Any sugestions?

 

Your system is probably low on R134. It has enough for the system to cycle but it does not take much for the compressor to suck the low side down to 20psi if the system is is undercharged causing it to cycle constantly. A good rule of thumb is your compressor should never cycle more than 8 times in a minute.

 

Mine is not as cool as it used to be. It always did take a long time to get really cold.

It checked about 15-20 psi then went to 50-60 psi between cycles. I hooked up a recharge kit and it now is 20-30 then 45-50 at 85+ ambient. It cycles about 6 times a minute. It only took about 1/4 of the can.

I checked all the positions and it works ok. I don't think there is anything wrong in the controls. Both heat and cold work ok. I don't get a lot of leaves collecting on the hood either so I think it is clean inside.

It eventually cools but it takes a good 1/2 hour to cool off when it's been sitting in the sun. black truck.

 

not enough refrigerant

 

tint the windows dark and turn the a/c up LOL realy i would get the truck checked and add the refrigarent by pounds not PRESSURE

 

what is your high side (big Red side) pressure and what is the temp outside... You most likely do not have enough refrigerant in that system...

Harold