the a/c in my 1999 ford f150 will cool then get hot like the heater is on then after a while will cool again. freon level is good

1st thing you would want to know is, if the compressor turning off or running during the time it gets hot.

How did you determine the system was fully charged?

compressor is running when air is hot. checked freon with gage

Ok.... What are your High & low pressure reading and what is the ambient temp. Is the system cycling? How low is the low side going before it cycles. Also try pinching off your heater hoses to see if that makes a difference........

high is 225, low is 50 ambient temp. is 85-90. system is cycling. dont know how low before it cycles. will try pinching hose tomorrow

thanks sidom

pinching off heater hose seems to have made a difference. now what should i do? can i run the vehicle with the hose pinched off safely?

Well, it's not like you're gonna overheat you truck doing that. Plenty of people are driving around with plugged heater cores which basically is what your are doing....

So the vent temps are normal now the lines are blocked off? If that's the case then sounds like you are having a blend door problem. If it's just doing it under low vacuum conditions (hard acceration) then you might get by with installing an addition vacuum storage reservoir due to a weak vacuum motor.........

That blend door actuator is electric on that one.

Here's what it looks like
and instructions to change it. They say the whole dash has to be removed but you may be able to sneak it out.






78 Corvette Pace Car For Sale-18k mi orig-Florida




(This post was edited by Hammer Time on Aug 2, 2009, 3:10 PM)

thanks sidom and hammer time for your help.

Here's what the motor itself looks like.








78 Corvette Pace Car For Sale-18k mi orig-Florida