Coolant temp running high wih A/C on.

Whenever driving in town with the A/C on my coolant temperature will go up rapidly, turning the A/C off and the temperature will go to normal again after 1-2 minutes. A/C blows cold and driving without A/C temperature will stay in the normal range. what should I check first?

http://tinypic.com/ei2g51

If your coolant system is properly maintained I would say the fan clutch is bad. also a dirty radiator will do it..

the coolant system must be clean. remove the top hose and look into the radiator coils for blockage..

thermostat could be sticking..replace these every 4-5 yrs.. I would do an external test to be sure the old/new is working correctly..

the added heat from ac is more than the engines cooling system can handle...this problem can be a little of all these items, not just one.

almost forgot leaks and or low coolant pressure...with no coolant pressure the coolant will start to boil...at high altitudes this is a bigger problem as the coolant boils at a lower temp....water pump cannot pump air.

Nice truck. How hot in degrees F? If the coolant gets too hot, it will pop the radiator cap and the coolant reservoir will fill up in a hurry, where applicable. Some possible issues, water pump--thermostat--radiator fan. I'm sure I'm leaving something out. Maybe the coolant system needs to be flushed?

Theres a good chance your radiator fins are clogged not letting it get enough air to cool the radiator. Most people don't realize that when they spray down the condenser it doesn't clean the radiator. Had to take my radiator off every 40,000 miles because of the areas I drove throw that would clog it up. If you've never cleaned it its a very good chance thats it. Take top cover on radiator off and lean radiator out to look at it, then you'll know. Good luck, Fiserman

it is a possible that any of these things can casue the issue. low coolant levels, or old coolant, improperly mixed coolant percentages, as well as the wrong type of coolant in the vehicle can cause overheating problems. its also possible for an over filled a/c system or under filled to cause a motor to run to hot when its turned on as well as clogged vanes in the radiator and condensor coil.