Previa heater matrix removal - Previa Toyota Cars & Trucks

Question edited for clarity.
Question moved to model category.

Here are the Fuse Box Diagrams

Toyota Previa 1995 Pin Fuse Box/Block Circuit Breaker ...

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Apr 15, 2023 - Toyota Previa 1995 Pin Fuse Box/Block Circuit Breaker Diagram ; 1, Relay Heater ; 2, Relay Heater ; 3, (Headlamp) Relay Light ; 4, Relay Engine Oil.

Fuse Box Diagram Toyota

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Fuse box diagrams (location and assignment of electrical fuses and relays) Toyota Previa (1995, 1996, 1997). Toyota Prius (XW11; 2000-2003)...> ...

Toyota Estima Previa 2G fuse and relay

FuseAndRelay.com https://fuseandrelay.com > toyota > estima-previa

Designation of fuses and relays Toyota Estima Previa 2nd generation, locations of control units and their diagrams. Cigarette lighter fuse.

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In normal circumstances the heater wouldn't begin blowing warm air until the vehicle has travelled 5 miles - call it 5 minutes. That's because the thermostat only begins to open at around that mileage/time and allows coolant to circulate around the engine. Before that - there just isn't any warm coolant in the heater matrix.

After 10 miles/10 minutes of normal driving the engine will be at its correct operating temperature and the coolant will be hotter - as will the circulating coolant in the heater matrix. That's when the heater blows the hottest air.

If you're sure that the heater has lost efficiency it may be due to air being trapped in the heater matrix/coolant system, or a blockage caused by limescale/engine corrosion within the heater matrix itself.

To remove any trapped air, set the heater to maximum, remove the radiator cap/coolant bottle cap and let the engine tick over for 10 minutes.

If the heater matrix is blocked/partially blocked, drain the coolant system, refill with plain water, set the heater control to open .. and let the engine tick over for 10 minutes. Drain it again.

Refill again with plain water and add a can of 'radiator flush'. Follow the instructions on the can of 'radiator flush'.

Drain again and refill with coolant/water.

If the heater is still inefficient then the only option is to replace it - and that's not an easy job.

could have a blockage in the heater matrix , drain the coolant system and reverse flush through to see if that will clear the matrix refill and test ,if you are able to disconnect the two hoses to firewall clamp them off and remove then flush the matrix through then refit hoses if the flush goes through ok, try this one first as less work for the same result , if still no heat remove the matrix for inspection etc

what radiator, there are many.
cab heater, engine RAD, tranny, A/C what?
the glove box, open it and remove the oper. guide, lost that , get one for best safety.
fuse box, there are 2, one (LHD car) at left ankle
and one in engine bay. LHD = left hand drive,
even causal looking finds both, do look.

best, violet, is to post symptoms... or are you just curious?

the crummy haynes
http://www.ebay.com/itm/Haynes-Toyota-Previa-1991-1995-Auto-Repair-Manual-/380500687864?pt=US_Texbook_Education&hash=item58979bbbf8

the book lost, oper guide
i use fleabay, put a watch on this search, then wait from one to pop up.....

http://www.ebay.com/sch/i.html?_odkw=Toyota+Previa+operators+guide+1995&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.XToyota+Previa++manual+1995&_nkw=Toyota+Previa++manual+1995&_sacat=0

1) Drain engine coolant. 2) Remove all cowling under the centre of the dash for access to the matrix.3) Remove two water pipes from matrix.4) Disconnect heater matrix valve cable.5) Remove matrix being careful not to spill water over the ECU.
Reverse instructions for refit.
6) With heater turned to maximum heat, top up cooling system with 50/50 anti freeze/water ratio.
Run vehicle and check that the radiator is free of all air and that the radiator fan cuts in when hot.
Run the car and recheck coolant level over the next few days of running in case of leaks.
Check under dash in case of leaks.

make sure theres the correct amount of coolant in the radiator and there are no blocked pipes including air preventing the matrix getting warm....is the matrix getting warm?

Removal & Installation It may be necessary to remove the upper radiator shroud to perform this procedure.

1. Open and support the hood.
   
2. Disconnect the negative battery cable and wait at least 90 seconds to proceed working on the vehicle.
   
3. Disconnect the power steering and coolant reservoirs.
   

Disconnect the coolant reservoir

4. Disconnect the coolant reservoir and power steering brackets from the side of the heating unit box.


Remove the coolant reservoir bracket from the side of the heater unit


Separate the power steering reservoir bracket from the side of the unit also

5. Remove the two bolts that attach the upper and lower portion of the heater box. 6. Disconnect the control cable on the side of the heater unit box.

Disconnect the control cable on the drivers side of the unit

7. Remove the eight nuts retaining the unit.


Remove the nuts (8) from around the heater unit


There are 4 nuts on each side of the unit

8. Disconnect the heater control valve bracket from the heater box.

9. Separate the top of the control box from the bottom.


Separate the upper case from the lower

Do this on the weekend ; )
You have to remove the complete dash to do this job.
Handbrake console.
Gear lever console, (radio/ashtray etc)
Lower driver side & passenger side.
Glove box.
Both side panels.
All these parts of the dash need to be removed near that order so you can see the hidden bolts/screws.

I've heard guys force matrix in and removing less, because they use soft pipes for matrix... but... not my thing.

most heator matrix replacements involve removing the dashboard

window wipers off remove trim and there is 10 mm nuts, remove them, remove speedo cluster and radio etc, there is 2 10mm bolts below each end in footwells at end bottom of dash, 1 bolt below your ash tray in front of gearstick, u got to get gear stick surround out.