Even though temp is at normal running temp.. flushed system 4 times, used engine coolant cleaner/flush, new water pump/leaked, t stat and gasket,heater core/leaked, still heat mildly hot!! had doors checked by two other techs, operating properly.
I have the same problem with my 95' mx3 and i just put cardboard infront of the the radiator and it seemed to fix the temperature problem its the cheapest fix anyone has ever heard of and it gets the job done but make sure you take out the cardboard when the snow melts ha
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when vehicles get this old and maybe there fluids havent been kept perfect over the years then yes due to sedaments in the cooliing fluid the heat core tends not to get as hot as it did when new , you can try a coolant flush , run heater while proforming a "hot" flush but do use all the normal precausions when dealing with hot engines
Hello, when the last time you have had your truck coolant system serviced? The anit-freeze needs to be reomove the coolant system flushed out (cleaned) Also, maybe a sticky themrastat and it will need to be replace along with a new radaitor cap.
. Clean the radiator inside and out---flush the inside with flush cleaner especially designed for auto coolant systems. Flush the engine block this can be done with the radiator at the same time. Replace the thermastat replace the radiator cap with the correct pressure cap. GB...stewbison
Thermostat.? if you haven't? Do it first then try it. While the car is running for a while touch the heater hoses that lead to the firewall. if one is cold and one is hot? You have a blocked Heater core. Follow the hoses back to the engine. Unconnect them both. By using a garden hose flush out the heater core do one side and then reverse by doing the other hose Lots of junk will come out so be care ful. Mistake people make is "Flushing the system" That doesn't mean your flushing the heater core. Seeing that you have done everything else it could be the thermostat which you didn't list or the heater core being clogged. When you finished installing the thermostat and flushing the heater core out. Replenish the coolant system . If you have a bleeder on the thermostat housing? use it . loosen it and top off the fluid until you see fluid comeout of the bleeder. The system being air bound would cause no heat..
replace the thermostant again this time get a hotter temp thermostant and buy it from the dealer, the other thing is that these cars are known for the temp sensors being bad this would give you the false reading on the gauge but would not affect the heat, if its taaking a long time then i would replace the stant and this time or before replacing the stant i want you to flush out the heater core, remove the hoses from the heatercore and use a water hose to flush water through the heater core, a plugged core will not throw heat or will start to allow water to flow when it gets good and hot to flow through the retricted core due to rust and crud, try the flush first and then try a new temp sensor if the flush helps the heat, hope this is helpful good luck.
It may be a problem with your vent control system in your dash. You have a vacuum supply that comes from the top of your engine and travels through your firewall and under your dash to be used to activate the movement of your vent controls. If you have a break in this vacuum line, your vents will not move to change from cool to hot air regardless of where you put your control dial. That could be your problem.......... or your heater core could be plugged. The core is a mini rad that is under your dash. It takes in hot engine coolant and acts as the heat source. This mini rad sometimes plugs up from ordinary use. Deposits slowly gather up and eventually clog up this rad making it useless. This rad may need to be replaced. Even though your pipes going under your dash are hot, the flow is probably very very slow and not giving enough flow to create heat for you inside your car. You maybe able to flush out the mini rad by waiting till the engine is cold, then disconnect both hoses under the hood going under the dash, blow out most of the coolant remaining in the heater core(if you can)( also be careful of your eyes) then block one of the lines and put some rad flush through the other line(use a funnel with a hose attached). Leave it there for a while then try running water through it with a garden hose. Be careful to not splash the rad flush fluid in your eyes(wear safety glasses and also wear gloves. Repeat if you feel. Try to flush out as much of the rad flush as you can before reattaching the hoses. Remember to add some coolant cause you will lose some. It would be better to add coolant to the heater core before you attach the hoses to get most of the air out of the system. Good luck
I've had this problem. 2000 GMC uses a closed coolant system. Meaning takes and returns coolant from and to the Reserve Bottle and has little air in the engine and heater systems.
If everything appears ok but no heat. "Air Lock" is the most likely cause. (With interior heater set to full heat) Solution; 1. Make sure water pump works. 2. Drain about 1/2 engine coolant into container. 3 Remove both heater hoses from engine side and flush heater core in both directs through heater hoses with garden hose. 4. Reattach heater hoses in correct locations. 4. Refill engine with coolant. 5 Start engine and run for 2 min., use caution when topping up coolant.
6. Most 2000 GMC have twist off caps with plugs located mid way on heater hoses. with engine cold, start engine these caps may be loosened to allow trapped air to escape. Do not attempt with engine hot due to hot coolant injuries. This may take more than one attempt to remove all air from heat system. 7. Lastly most 2000 GMC water pumps have a bleeder plug,( 3/8" square driver plug) located on the water pump. With egine cold this plug should be removed to remove any air. Reinstall plug with thread sealant.
Hope this helps cheers
It could be the impellor wearing out on the water pump, though I have not heard of this issue in your make of car, I have seen it first hand in other makes. The thermostat may not be opening up all the way, flow restriction,. The coolant temperture sensor could be going out, and the gauge in the dash could be going out. You could have flow restrictions else where in the engine. Have you ever had the engine flushed? these are the things that I can think of that would make your engine run hotter than normal.
Did you mean the only time it blows hot air is under acceleration?
First thing check the coolant level in the radiator. If coolant is low the first hing to stop working is the heat.
If the coolant level is fine but the coolant is muddy I woulds suspect a plugged heater core. You can try back flushing it by removing both heater hoses (engine cold) and then use a garden hose to flush clean water through the heater core. Do this on both pipes going into the heater core. Keep flushing until the water runs clear. Re attache the the hoses, remove the radiator cap, start the engine, let the engine come up to temp and top off the radiator with straight coolant (to comp for the water in the heater core). You may have to repeat this process several times over several days but you should be able to get it cleared enough to get sufficient heat without having to replace it.
If electric fans are coming on, and you have filled the system with the heater turned on high to purge it of air, even though you flushed it, I'd have the radiator flow tested (even when flushing, coolant tends to go around internal blockages, limiting its ability to work correctly) otherwise you need to begin testing from square one like you had never seen it before (don;'t assume anything you did is working) Pressure testing of coolant system, hydrocarbon test at fill opening and engine compression tests are important as well as what I mentioned above.
There are known problems with this vehicle's heater core not getting enough coolant flowing through it to blow hot air.
1) Even if the coolant looks good, there are problems with the heater
core plugging up. One solution is to use a heavy duty cleaner (CLR pipe
cleaner) to back flush the heater core. To know if the heater core is
plugged up, disconnect the 2 heater hoses at the heater core and
somehow connect a hose to one end of the core. Try to flow water
through, it doesn't have to be high pressure, and there should be a
steady stream. If not, try to get the cleaner directly into the heater
core and let it soak. Then back flush it and a lot of scale should be
seen coming out.
2) The other problem is that since the heater core is the highest point
in the cooling system air tends to get trapped in it. This should only
happen if the coolant goes low or someone has opened the system to
service it. There are a number of ways to bleed the system (vacuum
bleed, pressure bleed). One of the hoses should have a small hole in it
for bleeding air, pull that hose back just enough so the hole allows
coolant to flow out of it. Then accelerate the engine and get a good
flow coming out, when no more air bubbles are present, there should be
3)I've heard of bad water pumps with low flow causing issues as well as
an aux. water pump not fuctioning correctly leading to poor heat output
from the heater core. Someone should confirm this as I cannot get much
information on the aux water pump(electronic pump by the alternator
that is supposed to run after the car is shut off).