Today we are looking at the somewhat mammoth task of removing and replacing the heater core in a 2002 NM Pajero. In 99% of cars replacing the heater core and/or the ac evaporator is a pain in the butt, and although not that difficult doing this job on the Pajero is certainly time consuming, conservatively I would allow 8 hours for removal and replacement, providing nothing goes wrong and you have all the tools (and patience!) required. Just to give you an idea I’ve already spent 10 hours on the removal although this does include documenting and photographing the steps, and numerous coffee breaks :).
Speaking of tools, at a minimum you’ll need 10mm, 12mm and 14mm sockets and spanners, phillips head and flat blade screwdrivers of different lengths, vise grips or multi-grips and a lever or large screwdriver and a flexible shaft magnet tool is also a good idea if you happen to drop a screw or two. Organising the nuts, bolts and screws that you remove is a must if you want reassembly to go without problems. I used two large clip-seal sandwich bags, one for the left (passengers) side and one for the right (drivers) side. All screws, nuts, bolts and small components taken off from each side went into their respective bag as they were removed. This way suits me, you might prefer to bag each components hardware separately. Naturally you will also want to make sure you have plenty of light and park in an area where you can open both front doors all the way without knocking any paint off.
Before we begin there is a couple of issues we must cover –
- I haven’t yet found a way of replacing the heater core without disconnecting the a/c pipes at the firewall. To do this the refrigerant gas must be evacuated from the system first and this can only be done by an authorised person. Also if you have it the dual a/c system holds around a kilogram of gas and it’s not a good idea (and it’s also illegal) to go letting that off into the atmosphere.
- We are dealing with two airbags while doing this job and the system must be deactivated and the components dealt with carefully. See this link for important info on Pajero Airbag Safety.
Ok, on with the show. Now please keep in mind this write-up is not gospel, it’s just the way I do things and if you have any better or easier ways of doing things please let me know.
Pajero Heater Core Removal
The first thing to do is drain the cooling system, or at least drain it below the heater hose level if you aren’t planning on replacing the coolant. The easiest way to do this is with the bung on the left-hand-side bottom corner of the radiator. While you’re at it remove the heater hoses at the firewall (heater core) end. Our’s starting leaking during summer so I bypassed it until we absolutely needed it again 🙂
These hoses can be difficult to remove and the best advice I can give you is to grip the hose and try and twist it while pulling back on it. Don’t just go trying to yank it back, they develop a bit of a seal after a while and the only way to break this is to get the hose twisting around on what it is attached to. Failing that, a tool like the one shown below is a great help, sneak the tip of the tool under between the hose and the pipe and then run it around as much as you can to break the seal. A word of caution though, it can easily puncture a hose if used with too much force!
With the vehicle parked where you will be working on it we can now remove the negative battery terminal and insulate it by wrapping it with electrical tape or similar. The reason we do this is for Airbag safety, to prevent the lead earthing anywhere (the bodywork etc) and therefore providing a circuit to it. We don’t want an airbag deploying unnecessarily!
Removing both front seats will give a lot more room to work. Each seat has two 14mm nuts at the front and two 14mm bolts at the back. If you have an electric drivers’ seat, after removing the bolts and nuts tilt it back and disconnect the electrical connector and harness clip.
We can now start on removing the rear and centre sections of the console. Lift the center cup holder section up and out.
Underneath you will find two screws that need removing (and possibly the gross remains of something McDonalds as I think I did!)
Now if you have an auto you can push down of the bottom half of the shift lever to reveal two screws, one on the side and one at the rear. Remove these and the lever will pull off. The transfer lever simply unscrews in the normal anti-clockwise way.
The middle section of the console can now be removed. The front clips in to the section in front of it and it can take a bit of getting out. There is also a electrical connector for the shift lights that has to be undone.
We can now remove the two screws at the front of the rear console section. There are also two screws located inside the console box that have to be removed (the two screws at the back on each side can stay, they are there to secure a/c ducting for the rear). Underneath this section there are electrical connectors for the power outlet and rear a/c that have to be undone before you can completely remove this section.
Next up remove the two screws from the forward-most console section and push down a little on the top and it will slide out. There is one main connector to disconnect for the antenna, rear a/c switch etc.
The CD changer can be removed now.
Next up we can remove the rest of the console. At the front on both side there is a screw with a clipped-on plastic cover and two screws at the back.
The centre dash fascia can now be removed by taking out the two screws at the top and then carefully levering at each bottom corner. The wider the lever the better, unlike the narrow screwdriver I used! The hazard light switch connection has to be removed also.
Now the RV Meter, Stereo and heater controls can be removed by removing the screws and associated wiring connectors and pipe from heater controls.
Then we can move over to the passengers side and remove the glove boxes. The top one has 5 screws securing it that have to come out. A bit of gentle persuasion may be needed to remove it.
The bottom glove box is removed by removing the two stops from inside and then allow it to fold right down and gently lever on the retainers on each side and pull it towards you and remove it completely.
BEFORE COMPLETING THE NEXT STEP READ THIS!! No jokes, airbags can kill so make sure the system has been deactivated before proceeding to this step. With the lecture out of the way 🙂 , remove the two 10mm bolts as shown and disconnect the electrical connection to the airbag. This connection has a green flap that has to be lifted up first and then will come apart in the usual way.
Now remove the three 10mm bolts at the bottom of the dash and the two found under the trim at the side of the dash.
Next up we can attack the drivers side. The panel below the steering column is removed with 4 screws (right-hand bottom one out of the picture obviously, have to fire the cameraman 🙂 ), it also has two clips in the center of each side and the connection for the dimmer. To remove the fuel door and bonnet catch cable, remove the two screws that secure each lever, bring the lever forward through panel slightly and then you should be able to manoeuvre the cable out of the lever and it’s bracket.
We can now remove the steering column surround and undo the four 12mm bolts securing the column and lower it out of the way. The surround has three screws, the rear-most one will require a screwdriver with a bit of length.
The instrument cluster surround can now come out. There are two screws in the top and the bottom is held in with clips so a little gentle persuasion may be needed here.
The cluster itself has four screws, two up top and two down the bottom.
Behind the cluster there is a 10mm bolt that has to be removed and the electrical connectors need to be released by putting a finger in behind them and pushing in the clips that hold them in place.
As with the other side we can now remove the two 10mm bolts found at the side of the dash underneath the trim piece and the one bolt at the bottom corner of the dash. The electric mirror and fog light connections need to undone also. These can be a bit of a pain but with the outer trim piece removed you should be able to squeeze your hand in there and find and release the clips.
Both side pillar trims now need to be removed. The handles are removed by prising out the trims above the screws and removing the screws. The trims can then be pulled out from the pillar by hand. They have one clip and a locator on the back side.
Back to the center of the dash and there is two 10mm bolts on each side that need to be removed and the climate control sensor wiring needs to be disconnected.
All going well at this point dashboard shell will come apart from the rest of it with a bit of persuasion. It is secured at the top by three lugs, as shown in the second pic, which is why it will take some persuading. Be sure to check for wiring etc that is still connected while doing this. Once out be sure to place it somewhere where it’s not likely to get damaged or twisted out of shape.
From here we can remove the two ducting pieces on either side of the center of the dash frame.
To allow for the heater core removal without removing the entire dash frame (and potentially saving an hour or more work) I decided to remove the center piece of the heater box and loosen the blower motor housing. This as well as pulling the dash frame back gave me enough room. If you were replacing the a/c evaporator you would need to completely remove the heater and a/c box, and therefore the dash frame, from the vehicle.
To begin with we need to remove the bracket and 10mm bolt.
And remove the ducting bracket screw on the passengers side and take the screw out holding the wiring harness to give more room for removing the ducting. Removing this ducting is much easier when the blower motor housing is loose, which is coming up in the following steps.
The blower motor housing is held in by one 10mm bolts and two ‘nuts’ I suppose you could call them that you will need vise grips to remove. I also removed the two electrical connections from the bottom of the housing to allow it to move about more. There is also a 10mm bolt down below that connects the blower motor housing to the center piece that can be removed now.
There should be enough movement in the blower motor housing to remove the top section of ducting. Once this is removed the two brackets that hold the a/c pipes to the housing can be taken out.
The center section of the housing can now be removed to give more room to remove the heater core. The bottom section is held to the top section by four clips, two at the front and two at the rear and an 8mm/Phillips Head screw and the fan speed resistor wiring connector. Once the bottom section is removed the top should come out easily enough.
Next we can start to remove the bolts that secure the dash frame to the vehicle which will allow us to pull the frame back for more room to remove the heater core. There’s two 12mm each side and two 12mm each side towards the centre and three 5mm Allen Head bolts in the driver’s side door jamb to remove. Yes, the last pic was taken during reassembly 🙂
And in the engine bay we have two 12mm nuts that need to be removed. They are located on the firewall, to the right of the brake master cylinder, under the wiper motor. At this point it is also a good idea to undo the a/c pipes at the firewall, two 10mm bolts for this.
I found levering out the drivers side first and then levering out the passengers side a bit worked best, the pic below shows the movement you should get on the drivers side, the passengers side will probably be a bit less.
All going well you will be able to remove the bracket securing the heater core pipes in place and start sliding the core out.
You will have the wiring harness to get around and you may have to move the blower motor housing around a bit (just keep in mind that the back of this housing is hooked around the a/c pipes so you won’t get a great deal of movement but it should be enough).
The pipes can be angled around to make life easier. We quickly found out that the join where the longer of the two pipes joins the core was fractured on ours which would explain the sudden deluge of coolant in the cabin. One small twist and away it came!
Ok, this is where we’ll leave this part of the tutorial, in Part Two we’ll cover fitting a new core and getting this mess back together again. This article has been a big effort so if see something I’ve missed or something that doesn’t make sense or perhaps an easier way of doing things please let me know!