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Unread 12-04-2007, 07:24 PM   #1
jeepunlimited
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no heat ? flush heater core ?

hey guys, my 93 grand cherokee doesnt have very warm heat. It has new heater hoses, new coolant and a new 195 degree thermostat, its leaking a tad bit of coolant from the drain **** but nothing to get in a pinch about.

I am thinkin maybe my heater core is possibley plugged up, what would be the best way to flush it ?? i was thinkin of removing the heater hose lines and using a pressure washer ?? but would a pressure washer cause damage to the heater core?? i dont wanna pull the dash at all...i just want to try to flush it out , i have tried with a garden hose twice, the heat comes back for 1 day good as new, then slowly fades,

any ideas on whats the best way to flush the heater core guys ?

also could the rad cap have anything to do with temp of heat ?? like pressure in the system ?? my dad put a different rad cap on it cause the old ones spring was weak and leaking a tad bit of coolant ?? could a cap be the cause of no heat ??

also the jeep gets up to operating temp everytime i drive it , and there are no overheating problems what so ever.

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1993 Jeep Grand Cherokee Limited
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4.0L , 42RE transmission-- 242 selectable transfer case
Bone Stock with the acception of a K+N drop in filter and my aftermarket stereo, also did alot of new tune up wear and tear parts!
366 000 kilometers and stilll runs great :)
purchased for $125 bucks, amazing daily driver for the money
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Unread 12-04-2007, 07:42 PM   #2
jeepunlimited
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anybody chime in ?
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1993 Jeep Grand Cherokee Limited
Green/Gold, Tan Leather
4.0L , 42RE transmission-- 242 selectable transfer case
Bone Stock with the acception of a K+N drop in filter and my aftermarket stereo, also did alot of new tune up wear and tear parts!
366 000 kilometers and stilll runs great :)
purchased for $125 bucks, amazing daily driver for the money
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Unread 12-04-2007, 08:37 PM   #3
SJZ
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Quote:
Originally Posted by jeepunlimited
hey guys, my 93 grand cherokee doesnt have very warm heat. It has new heater hoses, new coolant and a new 195 degree thermostat, its leaking a tad bit of coolant from the drain **** but nothing to get in a pinch about.

I am thinkin maybe my heater core is possibley plugged up, what would be the best way to flush it ?? i was thinkin of removing the heater hose lines and using a pressure washer ?? but would a pressure washer cause damage to the heater core?? i dont wanna pull the dash at all...i just want to try to flush it out , i have tried with a garden hose twice, the heat comes back for 1 day good as new, then slowly fades,

any ideas on whats the best way to flush the heater core guys ?

also could the rad cap have anything to do with temp of heat ?? like pressure in the system ?? my dad put a different rad cap on it cause the old ones spring was weak and leaking a tad bit of coolant ?? could a cap be the cause of no heat ??

also the jeep gets up to operating temp everytime i drive it , and there are no overheating problems what so ever.

With the engine up to temperature, feel the heater hose to see if they are hot. If they are, you are getting a flow thru the heater core & flushing will not cure the problem.
You can flush the heater core via the heater hoses, but DON'T use a pressure washer, or you'll be soaking up water from the passenger's floor, after you blow out the heater core. Use a garden hose & don't do anything that could build up pressure in the system > ~18#.

In my opinion, you probably have an issue with the positioning of your mixing/blend doors. The heater core is getting hot, but the air isn't being channeled into the cabin.
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Unread 12-04-2007, 10:17 PM   #4
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Are you getting any air flow from the vents at all?
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Unread 12-04-2007, 10:24 PM   #5
CLASH
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sometimes my heat/ ac will just randomly shut off then if I let off the gas it will start blowing again. what would cause that?
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Unread 12-05-2007, 09:14 AM   #6
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Does it shut off or blow through the defrost?
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Unread 12-05-2007, 10:20 AM   #7
jeepunlimited
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i get air through the vents all the time, just sometimes it isnt hot, the heater hoses are burning hot, i cant hold them for very long at all, and they are both hot as hell...feed and return to the heater core

how would i go about checking the doors to the cabin ?? is there a way to open them to heat and leave it on it , like dissconnect the doors soo they cant close ?? is there any way i can work with the doors to get maximum heat out of it , i dont have AC soo im not worried about it , the old owner removed the AC compressor and idont mind not having ac at all, i just want heat!!!

would there be a explanation as to why it wont be that warm but then after driving it for a bit, it starts to heat up the dissapears again when i shut it down and start it back up ???? , would the digital unit in the dash have anything to do with doors not opening correctly ?? or should i dig under the dash to figure it out

also the positioning of the heat doesnt change at all, if i have it on floor, its on the floor, if i have it on defrost, its on defrost , , doesnt move the air flow until the dial is turned

any help would be great

thanx guys
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1993 Jeep Grand Cherokee Limited
Green/Gold, Tan Leather
4.0L , 42RE transmission-- 242 selectable transfer case
Bone Stock with the acception of a K+N drop in filter and my aftermarket stereo, also did alot of new tune up wear and tear parts!
366 000 kilometers and stilll runs great :)
purchased for $125 bucks, amazing daily driver for the money
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Unread 12-05-2007, 10:53 AM   #8
CLASH
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Quote:
Originally Posted by FPKites
Does it shut off or blow through the defrost?
it blows through the defrost. what does tthat mean?
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Unread 12-05-2007, 11:05 AM   #9
FPKites
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Vacuum leak
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Unread 12-05-2007, 08:01 PM   #10
CLASH
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ok. how to I go about finding the leak. and how to fix it.
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Unread 12-05-2007, 09:22 PM   #11
FPKites
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Google is your friend Clash - search finding a vacuum leak and you'll find loads of resources.

Search the forum too.
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Unread 12-05-2007, 09:32 PM   #12
CLASH
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okkk. ill do some searching
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Unread 06-07-2009, 01:25 PM   #13
jeepin4evr
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Thread Resurection

Hey Did you ever get your heat problem fixed? I am having trouble with my lack of heat and finding the solution.
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Unread 06-07-2009, 03:59 PM   #14
cmonson
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Instead of taking the easy way out (dont worry we are all guilty of it sometimes), just replace the 17 year old heater core. It is about 1 days work, but then it will be good for another 15 years.
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Unread 12-22-2009, 08:43 AM   #15
jvetter03
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So.....I know this is a really old thread, but i have to ask.....what do you do if the previous owner put a few (more than 2) tubes of stop leak in there? ...my buddy is having this problem right now. Thermostat was plugged up, heater core is plugged up...there was even a glob on the back of the radiator cap....WOW..... is there an easy solution to clean all that crap out so that the heater will work again
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