Car , my Suzuki SideKick ® is an Ice Berg or like a block of ice.
The Cab heater, has weak heating. MPG at horrible?
The ENGINE runs cold, the cab heater don't work or is weak? Cut to the Chase and get the right thermostat !
I will call the Radiator the RAD, and the thermostat the STAT. (yes, lazy) For those with a leaking CAB HEATER CORE SEE THIS.
I cover all the possibilities on my overheat page, but this page focuses directly on the frigid problem.
You lack cab heat from your cars interior cab core heater box.
Safety: Never remove the Radiator cap on a hot engine.
First off, lets tick through all the possibles of cab heater failures. (CHECK ALL fuses first , if fan fails)
If the motor can't hold 180F or more , fix that FIRST ! Use an IR gun , to the STAT housing. (gun will read about 10f lower)
It takes only 3 things, to be warm driving.
Low flow causes poor performance.
Poor heater op's is caused by , lack of main loop water temperature (180f min) or lack of flow to heater core or blocked core, or lack of air flow through core.
Here is the thermal gram of my 1996, 16v sidekick using the IR gun.
Note the 10 deg. thermal drop on the heater hoses, at 60F ambient. On a really cold day this drop will be more.
If the fan in the cab runs, then good, proceed on to the next tests , but if it don't , you will have to repair that now. The Schematics are all here.
The first test is the check the temperature of the thermostat housing with an IR gun. (it should be 20 deg less than the STAT rating, here is 195 F stat.)
If you can't find , barrow , rent or buy a Harbor Freight IR gun for $10 then you must use the old shade tree tests.
Drive car at least 10 miles and get it fully hot. (the hotter the better)
Now, place your hand on upper radiator hose ( Outlet hose from engine) and fell it. if you can hold your hand on the hose then the thermostat is working.
Warning stay away from the fan.
If the hose is nice and roasting hot, (way hotter than shower/bath water 105F to 120F) and feels too hot, then the thermostat is working.
If the thermostat is working and the motor is hot and the coolant is hot ,then you have core failure.
By core failure I mean the core is not flowing coolant as it should.
If I had that problem , I'd immediately do my Fall semi annual coolant service which includes a full flush of the system and the engine block and I would take of the 2 hoses on the heater core circuit and back flush them forcefully. Make sure they are free flowing.
Force clean water from the tap to each heater core hose 1 at a time ( not full pressure ,just a steady gentle flow)
If the core tubes are blocked and you can't get them clean this way , there is no other way to fix this issue other then removing the Core using this link page, for HVAC.
The only trick I know to help clean a core is to find real radiator cleaner, that is now banned by the freakn EPA. but can be found commercially.
The new EPA flush is the useless orange oil found as solutions to all things , it seems.
It is a caustic soda.( mix some up and Fill the core with it (plugged up at the hoses) and let it sit for 1 hour. Then flush it again.
safest is backing soda. ( these are what others have done, not me, nor am I recommending it, this information is just history)
Then sodium hydroxide (also called LYE or soda ash) in the form of DRANO, that has the aluminum chunks in it , that is sacrificial. (eats scale and not pipes).
This can wreck the pump seals , if they are weak. Todays cleaners are orange oil based and are near useless.
I'd do this to a RAD , sitting on the deck, but not the cooling system, total. The water pump don't like this trick !
With engine dead cold, can you spin the fan?, and not feel the fan slip? if its jammped up, it will be a fridged motor. Replace fan clutch. (if leaking its bad too)
If the fan don't spin, check the fuse to it and check that resistor block for open resistors. (use an ohm meter , with power off (key in pocket)) (the resistors, good, will be shorted)
Check that the Fan switch works (it is just a simple mechanical switch) , 12vdc power enters and exits on the speed pin you have selected. Nothing magical here at all.
If you have 12vdc up to the fan and it don't spin like crazy , it is bad.
Just like a bicycle or motorcycle, the cable sheath must be clamped to the body so it can move or all bets are off.
The cable center wire must move with the lever at the lever.
The cable center wire a the "business" end must also move with the lever.
don't the lever move trick , you can hear the damper pop closed with a loud THUMP.
if not? , the damper is INOP!
As stated in my overheat page that there is a TSB (trouble service bulletin) covering this issue. Read the TSB all Suz. PN's are there too ! look.
In 1992 (or near) the Intake manifolds were changed on all 1.6L (1.8L all have this) engines.
The Thermostat well 1.6L was increased from 1mm to 4mm (deep well) in the mid 90's , and use a simular seal like the 1.8L
If you fail to install the thermostat with the below O-ring surround seal the Thermostat will float, if it floats you will freeze. (seal is about 5mm think)
The 1.6L thermostat bleeder hole must be to the front of the car and all air burped from the top of the engine. (happens automatically with the bleed set right)
1.8L the bleed needs to be UP. 1.8L is called a SPORT Suzuki.
1.8L the must not have a clogged or reduced cab heater core, or tubing or the return path to the STAT will fail to hit the STAT thermal sensor, and the STAT WILL FAIL.!
See 1.8L coolant path details here. For 1.6L paths look here.
Air behind or below any STAT will cause the gage and the STAT to FAIL.
Rules: 1mm well = paper gasket only, 4mm well = oring ONLY, never ever both.
Rim well is the thermostat housing (lower)base rim. outer top edge, do not run paper on a 4mm rim or it will run frigid. (and not hold 195F)
I hope I didn't miss a cause and that this page helps in some small way.
Happy Kicking !
92-95 typical HVAC box. (Cami or Canada made). N. American autos.
rev:3 12-12-09 (3-2015 added J18 horrors and link)