Cherokee Overheating Help appreciated - Pirate4x4.Com : 4x4 and Off-Road Forum

JEEP THANG · 07-15-2005, 10:10 AM

K, so here are my wifes ZJ Symptoms. It's overheating but only when the A/C is on. When you turn the a/c on the jeep immediately lowers it's idle to about 600-650 RPM's and the jeep runs really rough. I just did an oil change, changed the air filter,spark plugs, cap n rotor and the coil, The tranny fluid /filter and replaced the uppr radiator hose that sprung a geiser the other day. Could it possibly be timing or some other part I missed. I haven't replaced the 02 sensor yet but I am going to do that tomorrow.
It's a 93 Grand Cherokee
242 4.0 Six
Auto Tranny and power everything.

thx in advance

animator · 07-15-2005, 10:13 AM

check thermostat?

JEEP THANG · 07-15-2005, 10:15 AM

thx, Didn't think of that. any Ideas about the Idle as well?

P.S. Love the SQL

broncobuster37 · 07-16-2005, 06:11 PM

Well I know nothing about Jeeps. But when you turn the A/C on you're working your engine harder so the idle may drop slightly. But I'd think they'd have something that would compensate for that. Just my theory...

unimog · 07-17-2005, 06:38 AM

Does it have the second electric fan in addition to the belt driven fan? I have just had to put a new electric fan in a friends Cherocar with AC. The fan was smoked and it had also blown the fuse. The fan comes on with the AC or at a certian engine temp.

Home Built · 07-17-2005, 06:03 PM

it sounds like the second fan is not coming on.
check for power at the fan plug. If you don't have any power at the plug on the fan then you may just need a relay.
if you do then time to hit the junk yard for another one.
there is a little vaccum thingy on the firewall that is supposed to raise the idle when the ac is on, but they are not adjustable. (at least mine was'nt)
you may need a new one of those to get the idle up. they create a small vaccum leak which raises the idle.

07-15-2005, 10:10 AM	#1 (permalink)
JEEP THANG Registered User Join Date: Jan 2001 Member # 3075 Location: Tucson, Arizona Posts: 37	Cherokee Overheating Help appreciated K, so here are my wifes ZJ Symptoms. It's overheating but only when the A/C is on. When you turn the a/c on the jeep immediately lowers it's idle to about 600-650 RPM's and the jeep runs really rough. I just did an oil change, changed the air filter,spark plugs, cap n rotor and the coil, The tranny fluid /filter and replaced the uppr radiator hose that sprung a geiser the other day. Could it possibly be timing or some other part I missed. I haven't replaced the 02 sensor yet but I am going to do that tomorrow. It's a 93 Grand Cherokee 242 4.0 Six Auto Tranny and power everything. thx in advance __________________ Today we did what we had to do. They counted on America to be passive. They counted wrong. - Ronald Reagan

07-15-2005, 10:13 AM	#2 (permalink)
animator Rapey Join Date: Sep 2002 Member # 13701 Location: Plano/Dallas Posts: 4,050	check thermostat? __________________ Think you're a marksman? Test your skills by joining the 200yd Iron Sight Challenge happening NOW in the OSR Forum: http://www.pirate4x4.com/forum/outdo...-may-31-a.html

07-15-2005, 10:15 AM	#3 (permalink)
JEEP THANG Registered User Join Date: Jan 2001 Member # 3075 Location: Tucson, Arizona Posts: 37	thx, Didn't think of that. any Ideas about the Idle as well? P.S. Love the SQL __________________ Today we did what we had to do. They counted on America to be passive. They counted wrong. - Ronald Reagan

07-16-2005, 06:11 PM	#4 (permalink)
broncobuster37 Registered User Join Date: Feb 2005 Member # 42509 Location: St. George, Utah Posts: 195	Well I know nothing about Jeeps. But when you turn the A/C on you're working your engine harder so the idle may drop slightly. But I'd think they'd have something that would compensate for that. Just my theory... __________________ Semper Fidelis

07-17-2005, 06:03 PM	#6 (permalink)
Home Built Registered User Join Date: Jul 2001 Member # 5734 Location: Redding Posts: 706	it sounds like the second fan is not coming on. check for power at the fan plug. If you don't have any power at the plug on the fan then you may just need a relay. if you do then time to hit the junk yard for another one. there is a little vaccum thingy on the firewall that is supposed to raise the idle when the ac is on, but they are not adjustable. (at least mine was'nt) you may need a new one of those to get the idle up. they create a small vaccum leak which raises the idle. __________________ [B]Chicks dig body Damage...[/B] 74 Chevy Fullsize, 39.5 Irocs, D60/FF14bolt, Locked, Lifted, Stroked, Fuel Injected, Hydro assist. with lot's of body damage...

07-17-2005, 06:38 AM	#5 (permalink)
unimog Registered User Join Date: Sep 2004 Member # 35525 Location: East Avon, NY Posts: 322	Does it have the second electric fan in addition to the belt driven fan? I have just had to put a new electric fan in a friends Cherocar with AC. The fan was smoked and it had also blown the fuse. The fan comes on with the AC or at a certian engine temp.

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