Tip & How-To about Heating & Cooling

Checking for problems in the heating system.

One main thing to try when trying to diagnose the heating system is to find the heater hoses. You want to start with a vehicle that has cooled down. Start the vehicle and feel the hoses. There should not be any change in temperature in the hoses until the engine reaches the 210 mark or whatever your vehicles normal engine temperature is. If there is a change before that mark then the thermostat is bad and needs to be replaced, it also needs to be replaced it the hoses never heat up. If the thermostat works fine next is to check the heater block. You can do this by feeling the upper and lower heater hose for a difference in temperature. The upper hose is always hotter than the lower but there should not be a significant difference. If there is a large difference in temperature. Than the heater block must be replaced.

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2 Answers

My 06 1.4 meriva blowing cold air have changed the thermostat but still no heat


No heat can be caused by numerous things. First, make sure the coolant level is full and all the air is bled out of the system. Next, bring the engine to operating temperature. Feel the hoses that go into the heater core. Both hoses should be close to the same temperature. If one hose is hot and the other is warm/cool, suspect a plugged heater core. A back flush on the heater core will usually correct this problem. If both heater hoses hot, there will be a problem with the internal heater box. Most likely a blend door motor that controls the hot/cold air function

Jan 19, 2016 | Cars & Trucks

1 Answer

How do I determine why 2003 Pontiac Grand Prix blows no heat with step by step instructions?


The most common reason is the coolant is low.
Check coolant level when vehicle is cool.
If coolant is low start vehicle and fill radiator with coolant.
if coolant was needed high probability there is a leak
look at all cooling system hoses, thermostat housing, all over the engine to try and find leak and repair.

if coolant isnt low, make sure its not really dirty...reddish mud colored. If it is the radiator is probably clogged and needs to be flushed thoroughly..then refilled with coolant.

there will be two heater hoses coming out of firewall..they are connected to the heater core and one hose directs flow of coolant to the heater core, other hose directs flow away from heater core..start vehicle and run until engine is warm then feel each heater hose as close to the firewall as possible..if one hose is hot and other is cool..the heater core is clogged and will probably require replacement. also look in passenger floorboard if coolant is leaking there..heater core requires replacement.

if you check these things and find none of the issues, let me know, and I will tell you what to check next.
Good Luck with it and if you have any.question let me know

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Sep 20, 2015 | Pontiac Cars & Trucks

1 Answer

my 1998 pontiac firebird service engine light came on and my OBD11 scanner produced 2 trouble codes PO125 ( insufficient coolant temperature for closed loop fuel control.the 3800V6 engine over heating and heater produces cold air only.l replaced the themostat and the(ECT)engine coolant temperature sensor but service engine light still on and scanner trouble code PO125 still on.What else would cause these engine over heating problems and heater not producing hot air, triggering a PO125 code insufficient coolant temperature for closed loop fuel control OBD11 trouble code and service engine soon light?


service the engine.. change oil ,filter plugs etc

did you clear the faults before each read
Diagnose Buick 3800 Engine
unusual code that

P0125 is the OBD-II generic code for the engine computer, or Engine Control Module (ECM), not detecting enough heat in the cooling system before the fuel management system can take control. The ECM has a predetermined value after you start your vehicle to expect a certain coolant temperature

P0125 OBD II Trouble Code Insufficient Coolant Temperature for Closed Loop...

ecm runs the engine cooling fans

3800V6 engine over heating and heater produces cold air
try these

EGR vale not working
overheating
inlet manifold gasket leaking
water pump fins corroded
soft radiator hoses
try a new radiator cap

internal heating
heater control tap stuck
directional actuator flaps stuck

Apr 16, 2017 | Cars & Trucks

1 Answer

How do you install a heater core for a1991 Mazda Navajo


remove dash assembly try to back flush first or drain cooling system put water back in add cascade dish washing soap and drive a couple days if heater starts woreking better turn heat on high run engine open drain with a hose nozel on high and a large pan under drain flush all water out with engine running refill system with heat on high and vehicle running if heat still weak remove heater hoses the top should be the return line put a hose about 8 inces long on both out lets run the bottom hose to a high area where it can be suspended put a funnel in upper hose poor clr into hose until it comes out top of lower hose let set for hour and a half then flush out with water into a clear jug flush water vthrough upper hose then if u have air compressor have a 6 inch hose attatched to upper pipe and blow out core into same jug until the jug has clean and clear water refill cooling system and drive if heat doesnt work at first put engine under a load to release residule deposits in heater core and it should start flowing

Apr 01, 2012 | Cars & Trucks

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