my dad has a 95 F150 with a 302 in it. well hes had it for bout 2 years and in the entire time hes had it hes had an issue with the AC. It works great but when hes driving around in town it goes off and on, off and on. but on the interstate its constant.


i remember (i think) there being a TSB on it. but not sure.

what could be the problem?

 

probably not keeping good pressure or the AC cluch is sticking. my dads 96 does the same thing. is there a howl when it stops putting out cold air? or dose it just shut off completely? if it shuts off completely then my guess is a short in the electrical somewheres

 

I had this problem with my 1995 F250 351W and it was low on fron, due to the schrader valve leaking. System cannot build enough pressure so it kicks off.
Check your AC system for leaks, recharge with freon and see if that helps.

CS45

 

I would suspicion two issues. Refrigerant charge is low, which needs to be confirmed with manifold guages, or the a/c clutch air gap is set too wide allowing the clutch to "slip out" at low engine RPMs.

 

Can you here the fans spinning, but no air coming out of the vents? My truck was doing that randomly. It ended up being a vacuum leak, theres a white line on the passenger side on the firewall that goes in this little valve that was leaking.

 

^i agree that stupid white vac lines breaks

 

ok. ill let my dad know to check that.

 

Is this line and valve under the hood? Mine has been doing what you described as well. I suspected a vacuum leak behind the dash, at the switch, or one of the blend doors, but my back was just dreading laying under the dash to search for it.

 

I'm bettin the low pressure cut off switch is just doing it's job, & your freon level is right around the level that triggers it.

 

its under the hood. when you lift the hood look to the passenger side and you will see a white line going into a valve....BE CAREFUL the white line can be very VERY brittle.

 

Mine looked fine until I took it off and saw underneath it.

 

ok. so my dad said it didnt appear as the line was leaking but said he thought maybe that valve wasnt staying open... IDK? maybe a possibility.

 

Off and on at low speeds, works ok on the highway.
That's not low refrigerant charge. Generally, the compressor will cycle more at higher engine and road speed because the low side pressure drops more and drops quicker.
My bet is that the fan clutch is very weak/dead and the compressor is cycling on the High Pressure Cutout Switch. Spray water over the condenser and see if it stops cycling and cools better.
That switch opens at about 375psi, so it's beating the compressor to death. Being a 95, the fan clutch is about 5 years past due, at least as far as the AC is concerned.

 

ok.. ill help my dad by doing that with him.