Question about 1991 GMC Sierra

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How do I remove a heater core

I have a 3500 5.7 motor is there any thing I need to know if I am doing it my self is it ok to by pass the core how long can I drive the truck if I did that

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It is ok to by pass the heater core but you will get no cabin heat in cold weather. find the 2 hoses that go into the heater core and join them together. Remember to check the coolant level at the radiator cap as you may get an air lock in the system

Posted on Nov 09, 2014


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Posted on Jan 02, 2017

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SOURCE: Heater core

I just changed my 1996 jimmy heater core. Its not that bad. It took about six hours.

Remove all panels below the dash. There are three nuts to remove under the dash, One in the center and one on each side at the side panels. I did not remove the park brake, I just let that panel hang loose. Remove the two nuts holding the steering wheel bracket top allow the steering wheel to rest on the seat. Remove the speaker covers on the top of the dash and remove the defroster grill. You'll see four screws on the top of the dash. When you remove them, the dash will start coming down. Where you removed the nut under the right side you will see the dash hangs on a pin right next to the bolt, lift the dash off this pin and you'll have more room to work. I loosened wire straps and tape as needed for more room to work.
The heater core cover is nearly rectangle on the right side. There are six screws holding in on. he first five are easy, number six cannot be seen without a mirror and light. I had an extra pair of hands to help with this part. The screw in the top left corner of the heater core cover is hidden. Use a mirror to see and place socket on it. Remove the cover. The heater core itself has four screws and two brackets that come off easily. Where the tubes go through the fire wall there is a bracket with one screw into the fire wall. Its hard to see and is not the screw mounting the clamps on the tubes. Go under the hood and remove the heater hoses. The heater core will slide right with some maneuvering. Reinstall the same way. It takes less time to assemble now that you have seen it.
I'm just a weekend garage mechanic and it really wasn't that bad, just take your time.

Posted on Dec 27, 2008

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SOURCE: Need to know if I am supposed to remove the dash

yes remove dash shold be one box to bring out

Posted on Jul 01, 2009

  • 252 Answers

SOURCE: how do you replace the

You will probably need new heater hose...first check heater hoses that run from engine to the
heater core......Most hoses will tear at the end where they are connected to the core and at the engine...First mark where each hose goes then drain coolant from system and remove both hoses...Take old hose's to parts store and get new hose's and clamps...They should be dryrotted
by the year of vehicle....It is easy to bend or break new core so be very careful when installing new core....After removing old hose's from core under hood you will know the location of the core....
remove screws under passenger side dash to remove core from inside of dash...very simple very easy....It looks like a tiny radiator with an in and an out spout...dont forget to mark where hoses
connect before removal.......Be sure and refill with new coolant/clamps/hoses because of age of vehicle...Both heater hose's that connect to the core are connected at the firewall on the passenger side of the engine...The core fits into the firewall dash and is connected to an input and an output hose...THIS IS EASY FOR BEGINNERS BUT BE CAREFUL WITH NEW CORE NOT TO BEND !!

Posted on Jul 29, 2011

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2009 jeep patriot 2.4 heater not blowing hot

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My 2010 Jeep Liberty doesn't blow heat. I let the air out and the heater core is not clogged.

no engine stated, 3.7L or diesel or what?
i cant bet past let the air out.
ok, i get it, you burped all the air out , after draining all coolant
my guess, is the heater worked before, must i guess that?
my guess is this, (wild , lacking full story)
your heater did fail before (touching it) and you then drained the system
that was a wrong move. now you get to get all those air pockets out to land you back to square one, no heater, ok Ill pretend you did that, the book, on jeep cover this, read them>?
  1. guess, 2, blower blows fast on high,say in A/C mode.
  2. I check fuses, and they are ok.
  3. I then check fluid levels and ok, (at RAD)cold. only'
  4. I then get engine hot, it must reach 180F, degrees if not we wnext, the HVAC heat steals engine heat, so...IS NEXT.pg7
  5. now the HVAC chapter tells you to put the HVAC in to full heat mode fan on high, and check the 2 hoses that pass from the engine to fire wall to the heater core, for both same temperature and min. 125f (see chart in SM) ,at 60f outdoors
  6. if this test passes, above, then there is no need drain anything. landing use where, we land on HEATER FAILURE
  7. the failure of air to pass through the core, heater and that is caused by only 2 things (mostly)
  8. The blend damper motor is dead,
  9. or the controls sad damper are wrong.
  10. many jeeps have an HVAC self test, Ill now look up that for you, try I will. chapter 24 in the SM service manual.
page 2 in that chapter covers all tests.
see 2, that is the blend door.
if stick closed, this is the first thing to fix.
i see no HVAC self test, in fact the book shows only the dealer
scan tools above to test it.
I'd still scan the PCM to see if there are errors using any scan tool
that is always wise and always first. on any modern car.
1 is heat core, air must flow there, or there will be no heat.
no heat parked, engine hot, set to max hot, and both recirc and fresh air mode fail, parked . !!!!

Nov 29, 2016 | Jeep Cars & Trucks

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Why would I not have heat? 2001 Dodge Ram 3500 truck. motor temp gets to 190 degrees after replacing faulty thermostat. but the heater don't blow hot air. blows cool to warm. everything moves and...

sounds like your blower motor is OK so either the hot water is not getting through the heater core, or the air is not being routed across the heater core. If the hoses or core are blocked, that would do it or if an air door is not allowing the air to the core.

Hopefully it won't come to core removal, but this video should illustrate what is going on. There are also videos for unplugging the core. good luck

Jan 08, 2015 | 2001 Dodge Caravan

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Turn on power to heater & nothing but the power light comes on, please help

There's a heater core box where radiator coolant passes through. When you turn on the heater, the fan on the heater core box blows air through the core, then the air is heated up and it passes through the air ducts, which leads to the windshield defroster, the vents, or your feet depending on where you set the control. If you're not feeling heat, either the fan on the heater core box is not working, or there's restriction on the coolant hoses and hot coolant isn't passing through the heater core box. Remove and diagnose the heater core box to ascertain the coolant lines are not blocked and the fan is fully operational. If the heater core box is OK, then the hoses have restriction to prevent hot coolant from passing through the heater core box.

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Great question dustin but the A/C is suppose to come on in defrost or mix mode- this is floor & defrost. Does not seem to make sense does it. One of the things the a/c does is remove the moisture from the air. You need warm DRY air to remove the moisture from the windows. An automotive H.V.A.C. ( Heating,Ventilation,Air conditioning) first forces air thru the a/c evaporator core then thru the heater core and out the selected vent. If you only want a/c a blend door will by-pass the heater core which is controlled by a hot/cold knob or digital temp cotrol on the dash. Now back to the cold air problem- assuming the basics are all ok- Coolant is full, Engine gets up to proper operating temp-around 195 degrees- upper radiator should be hot. Both heater hoses should be hot. If thats all OK the blend door might not be working. It is controlled by an electric motor called a Blend Door Actuator which are prone to fail. I have replaced many on ford vehicles. Hope this helps

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No heat I have changed thermostat,blow air thougt

I had this exact problem. Suspect a clogged heater core and you will probably have to replace it. Make sure you have the valve that opens the heater that works. You can remove it and see if it works. The valve is a vacuum valve that is connected within 10 inches of the 2 firewall heater hoses.

If the valve opens and stay opens and passes water well then disconnect the output of the heater and verify the that water flows well and you may be ok with the heater core being ok.
I know you do not like to hear but with all these tests, you should replace the heater core in the cab. It is a pain to remove but doable.


Sep 20, 2011 | 1992 Dodge Caravan

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How to replace a heater core

Heater Core Removal & Installation Front To Remove:
  1. Make sure you have the anti-theft codes for the audio and the navigation system, and then write down the audio presets.
  2. Disconnect the negative cable from the battery.
  3. From under the hood, disconnect the heater valve cable from the heater valve. Turn the heater valve arm to the fully opened position.
  4. When the engine is cool, drain the engine coolant from the radiator.
  5. Disconnect the inlet heater hose and the outlet heater hose from the heater core.
  6. Remove the mounting nut from the heater unit. Take care not to damage or bend the fuel lines, the brake lines, and related parts.
  7. Remove the dashboard.
  8. Remove the evaporator.
  9. Remove the mounting bolts and remove the heater unit. Front heater unit honda-10-00-4128.gif

  10. Remove the self-tapping screws and the clamp.
  11. Carefully pull out the heater core so you don't bend the inlet and outlet pipes.
Front heater core honda-10-00-4129.gif

To Install:
  1. Using care, install the heater core to the heater unit and secure.
  2. Using care, install the heater unit and tighten mounting nuts and bolts to 7 ft-lb (10 Nm).
  3. Install the evaporator.
  4. Install the dashboard.
  5. Connect the inlet heater hose and the outlet heater hose to the heater core.
  6. Connect the heater valve cable to the heater valve.
  7. Refill the cooling system with engine coolant.
  8. Adjust the heater valve cable.
  9. Make sure that there is no coolant leakage.
  10. Make sure that there is no air leakage.
  11. Connect the negative battery cable.
  12. Perform the power window control unit resetting procedure.
  13. Enter the anti-theft codes for the audio and the navigation system, and then enter the audio presets.
Rear To Remove:
NOTE: The rear blower motor, the rear heater core, the blower screen, the rear blower resistor (heating/air conditioning system) and the rear power transistor (climate control system), the rear air mix control motor (climate control system) , the rear mode control motor and the rear expansion valve can be replaced without removing the rear heater-A/C unit.
  1. Remove the self-tapping screws and the clamp, and then remove the bolts and the rear evaporator lines with the rear expansion valve. If necessary, remove the rear expansion valve. Use a second wrench to hold the other fitting on the valve so the rear evaporator lines won't twist. Leave the first fitting loosely connected so you can use it to hold the valve while you loosen the second fitting.
  2. Remove the rear heater hoses.
  3. If necessary, remove the rear blower motor, the rear heater core, the blower screen, the rear blower resistor (heating/air conditioning system), the rear power transistor (climate control system), the rear air mix control motor and the rear mode control motor.
  4. Remove the self-tapping screws and the lower housing.
  5. Remove the self-tapping screws, and carefully separate the left upper housing from the right upper housing. Remove the rear heater core.
Rear evaporator assembly honda-10-00-4116.gif

To Install:
  1. Replace the rear heater core.
  2. Attach the heater hoses.
  3. Make sure no air is leaking from the left upper housing and the right upper housing fitting and from the upper housings and the lower housing fitting.
  4. Before reassembly, make sure that the rear air mix control linkage and door move smoothly without binding.
  5. Before reassembly, make sure that the rear mode control linkage and door move smoothly without binding.
  6. Reassemble the housing.
  7. After reassembly, make sure the rear air mix control motor runs smoothly.
  8. After reassembly, make sure the rear mode control motor runs smoothly.
  9. Refill the cooling system and make sure that there is no coolant leakage.
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Oct 16, 2010 | 2005 Honda Pilot

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Heater system not working/heater value system /switches control working, but no heat, put theorstat in and no heat still/

Hello there :
What you are going to have to do is either check out the heater core by a shop or you can do it your self.
Check to see if all of the wires are connected to the heater motor and see if the heater motor is working if not replace it if it is working than i would then look into having the heater core replaced OK?

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Broken heater core in 2005 dodge ram 3500

The Heater core is difficult to replace on the RAM since it is buried in the plenum box. The box has a convenient door panel that you can open to remove and replace the core. The catch is that the convenient door is on the back of the box and you have to remove the heater box to get to it. This involves removing the steering wheel, steering column, complete dash panel, evacuating the AC, draining the radiator, and finally removing the heater box. Once you have the box out(8-12hrs), the core is simple to replace.

You want to be sure that the core is the problem before you undertake this process. If there is a strong smell of antifreeze in the cab or a puddle of coolant on the passenger side floor, the diagnosis is easy.

Check that the radiator is full, not the overflow tank, the radiator. On a cold engine you can remove the radiator cap and check the level. It should be full. If there is air in the system it will affect cab heating and engine cooling.

Another good check is to feel the two heater hoses going into the firewall from a cold start. The hoses should warm up at about the same rate and get uncomfortably hot-close to radiator temperature.

If the core appears to be OK, the next concern is with the blend doors that divert air through the heater core. This is a common failure on the RAM. Check for an explanation of the operation of the system and a fix for the common problems. The RAM has four different DC servo motor controlled air flow doors that are susceptible to failure and all of these need to be checked by either observing the symptoms of failure or reading the codes. The problems are easy to fix with the HeaterTreater kits, but the OEM dealer fix requires removing the plenum box as described above. It is a costly repair if you take it back to the dealer and are not under warranty.

Oct 10, 2009 | 2005 Dodge Ram 3500

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