crappy heat except for when accelerating
#1
Junior Member
Thread Starter
Join Date: Mar 2011
Location: Grand Rapids, MI
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1988
Model: Cherokee
Engine: 4.0
crappy heat except for when accelerating
Brand new heater core, new thermostat and still crappy heat when at an idle. I have to be accelorating to get it to produce anything remotely warm. Any ideas? TIA!
#2
Junior Member
Join Date: Jun 2011
Location: Ft. Meade, Maryland
Posts: 119
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1991
Model: Cherokee
Engine: 4.0l
#3
Junior Member
Thread Starter
Join Date: Mar 2011
Location: Grand Rapids, MI
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1988
Model: Cherokee
Engine: 4.0
Would you know specifically which vacuum line or the color? Ive done a million cores but theres a good chance something couldve gotten pinched!
#5
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Ditch the heater control valve, plug the vacuum line and don't look back.
#6
Junior Member
Thread Starter
Join Date: Mar 2011
Location: Grand Rapids, MI
Posts: 63
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1988
Model: Cherokee
Engine: 4.0
Thanks guys. If it had to do with the water pump, there would most likely be over heating issues right? Just seems logical to me...
#7
Junior Member
Join Date: Jun 2013
Location: SW Virginia
Posts: 89
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1999
Model: Cherokee
Engine: 4.0L
Ditch the heater control valve as cruiser mentioned.
Bleed the cooling system again. On most vehicles, when you have the systems you described, there is an air pocket in a heater line somewhere.
When you accelerate from a stop, does it ever sound like there is water/liquid trickling behind the dash? If so, that's a good sign there is air in the system. Good luck!
Bleed the cooling system again. On most vehicles, when you have the systems you described, there is an air pocket in a heater line somewhere.
When you accelerate from a stop, does it ever sound like there is water/liquid trickling behind the dash? If so, that's a good sign there is air in the system. Good luck!
Trending Topics
#8
CF Veteran
Join Date: Apr 2009
Posts: 4,734
Likes: 0
Received 9 Likes
on
9 Posts
Year: 2015, 2012
Model: Grand Cherokee (WK2)
Engine: 3.6L
If you get rid of the control valve, wouldn't you:
a. Lose the ability to modulate heat temperature on pre-97s?
b. Have straight engine heated water going in the heater core, even in the summer. Would it interfere/fight with the air conditioner evaporator, which is in the same box under the dash?
c. If it doesn't affect anything, why does it exist in the first place?
a. Lose the ability to modulate heat temperature on pre-97s?
b. Have straight engine heated water going in the heater core, even in the summer. Would it interfere/fight with the air conditioner evaporator, which is in the same box under the dash?
c. If it doesn't affect anything, why does it exist in the first place?
#9
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
A) No, as the heat is controlled by a door, not the valve.
B)Yes you would have water flowing through the heater core. And no, it doesn't interfere with or reduce the effectiveness of the AC since the blend door is closed to the heater core side and open to the evaporator side.
C) It was a redundant feature not to open the valve for heat but to shut it for AC operation. Totally unnecessary.
D) If it didn't work, I wouldn't have been doing it for years in Arizona.......
B)Yes you would have water flowing through the heater core. And no, it doesn't interfere with or reduce the effectiveness of the AC since the blend door is closed to the heater core side and open to the evaporator side.
C) It was a redundant feature not to open the valve for heat but to shut it for AC operation. Totally unnecessary.
D) If it didn't work, I wouldn't have been doing it for years in Arizona.......
#11
Renix Super Guru
Join Date: Mar 2008
Location: In yourz postez fissin jurr spelinzs
Posts: 24,653
Likes: 0
Received 16 Likes
on
12 Posts
Year: 1990XJ/1989MJ
Model: Comanche
Engine: 4.0L Renix
Some ppl use a brass gate valve in the area where the above picture depicts a plastic coupling. You would turn the valve to the open position to get flow thru the heater core and close it in summer months for A/C.
#12
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
#13
CF Veteran
Join Date: Aug 2011
Location: Nor-Cal Coast
Posts: 10,489
Likes: 0
Received 17 Likes
on
17 Posts
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
I fall with Blue. I want control of hot water circulating in the cab. Period. Granted with good AC, (likely running in AZ), the heat from it may not be a big deal, but if it's hot and I'm not running the AC, the last thing I need is a little 210* radiator in the cab.
Chick, I'm no real help. Yours sounds like mine which is pretty week unless I'm climbing a good hill. I figure it's my 1/2 clogged core. New Mopar 195* stat. It's shurely primed. Interesting point on the fins. Djb posted a Pic of one pump that was just a flat disk! There might be a point where it will still push enough through the rad, but still not be full strength. I should check mine, even though it's just 12 years old.
Did you watch the lever on your valve while someone turned the heat on/off? (you can see it move). And last. It's a round plate like a throttle plate, that controls the water flow. I saw one once that had deposits so thick on the backside, that when fully open, only 1/2 of the pipe was open. (so the opening was more a "D" than an "O")
Chick, I'm no real help. Yours sounds like mine which is pretty week unless I'm climbing a good hill. I figure it's my 1/2 clogged core. New Mopar 195* stat. It's shurely primed. Interesting point on the fins. Djb posted a Pic of one pump that was just a flat disk! There might be a point where it will still push enough through the rad, but still not be full strength. I should check mine, even though it's just 12 years old.
Did you watch the lever on your valve while someone turned the heat on/off? (you can see it move). And last. It's a round plate like a throttle plate, that controls the water flow. I saw one once that had deposits so thick on the backside, that when fully open, only 1/2 of the pipe was open. (so the opening was more a "D" than an "O")
Last edited by DFlintstone; 03-05-2014 at 11:55 PM.
#14
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,875
Received 1,526 Likes
on
1,238 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I fall with Blue. I want control of hot water circulating in the cab. Period. Granted with good AC, (likely running in AZ), the heat from it may not be a big deal, but if it's hot and I'm not running the AC, the last thing I need is a little 210* radiator in the cab.
Chick, I'm no real help. Yours sounds like mine which is pretty week unless I'm climbing a good hill. I figure it's my 1/2 clogged core. New Mopar 195* stat. It's shurely primed. Interesting point on the fins. Djb posted a Pic of one pump that was just a flat disk! There might be a point where it will still push enough through the rad, but still not be full strength. I should check mine, even though it's just 12 years old.
Did you watch the lever on your valve while someone turned the heat on/off? (you can see it move). And last. It's a round plate like a throttle plate, that controls the water flow. I saw one once that had deposits so thick on the backside, that when fully open, only 1/2 of the pipe was open. (so the opening was more a "D" than an "O")
Chick, I'm no real help. Yours sounds like mine which is pretty week unless I'm climbing a good hill. I figure it's my 1/2 clogged core. New Mopar 195* stat. It's shurely primed. Interesting point on the fins. Djb posted a Pic of one pump that was just a flat disk! There might be a point where it will still push enough through the rad, but still not be full strength. I should check mine, even though it's just 12 years old.
Did you watch the lever on your valve while someone turned the heat on/off? (you can see it move). And last. It's a round plate like a throttle plate, that controls the water flow. I saw one once that had deposits so thick on the backside, that when fully open, only 1/2 of the pipe was open. (so the opening was more a "D" than an "O")
Those HCVs are troublesome and dangerous pieces of crap. They'll strand you, blow up in your face while working under the hood, and don't allow coolant to freely flow through the core ALWAYS and keep crud from building up in the core.
I'm telling you. It frickin works.