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my 1988 f150 sb 351w auto when i put my AC on max it works great when i put it on normal it blows warm air???????? any ideas????
Thanks for any help or tips!!!!
James
Quite a number of problems could cause no cooling on normal ac. The system has to work harder to cool in normal ac because you are trying to cool down outside air. Start with making sure the condensor is clean, that's the coil in front of the radiator. Next make sure the fan clutch is working properly, it should be in 'high gear' when idling in the hot summer time and you will hear the roar of the fan when starting out from a stop. Also, if you stop the vehicle when it's hot, let it sit for about 20 minutes or more, then try to move the fan blade, you should feel resistance.
After you confirm the above, then it's time to look at the charge and this takes having the right equipment to check the system pressures. Sounds like you could be low on freon but it's worth checking the other things first. If you are low on freon, then the system will have to be leak checked and any leak fixed, system evacuation and recharge.