my 2003 grand cherokee recently started running hot only at redlights & slow traffic on 80+ degree days.If A/C is on it blows warm air at redlights..is this a tempature sensor issue?

Are your fans running? Look at fans first. If they are not you can test them by directly hooking them up to 12V. No particular polarity because they are DC motors. If they work check fuses and relays associated with fans. Yes it could be temperature sensor.

fan doesnt work while idling....but seems to come on when driving.Am not experienced n hooking up to 12 volt power supply

any suggestion appreciated!

btw fuses ok

Do they both (fans) come on when you turn AC on? They should. Give them up to a minute to come on. If not then they are bad. To hook up to 12V. Get 2 wires with alligator clips on each end and disconnect the pigtail at each fan and clip on each terminal of one fan at a time and then touch one wire to battery positive and one to battery negative. It should be instant running. You cannot hurt the fan motor. Do this with car off. Make sure to plug fans back into their pigtails if they are obviously good.