no heat

I need you to check something. Start the engine, let it warm up, have the heat on high, and feel both heater core hoses. They should both be hot. Could be a restrictive heater core or a blend door issue, Let me know what you find.
Joe

Go ahead and read this guide, it will help you figure out whats wrong

https://www.2carpros.com/articles/car-heater-not-working

pretty much like the subject says....the heater will work fine when dial is set all the way to hot,but when you apply the brake pedal the air turns cold,but doesnt allways go back to blowing hot when you take your foot off the pedal....any suggestions...ty in advance

Your heater core probably has a slight clog. Try flushing it out.

ty i will give that a try...but do you think it could b electrical?

No, what is happening is when you stop accelerating your water pump flows a lot less since the engine RPM is lower. Since the coolant flow is a lot lower, it is a lot harder to get fresh hot coolant into the clogged heater core.

If you are idling, try revving the engine to 2500rpm, you should feel the air get warmer.

ty,i see what your talking about and i just talked to the wife and she said it does when she slows down also,not just when the brake is applied so i agree and i will definately flush it...thank you so much for your time

how do i determine if the water pump or thermostat is bad??

waterpumps usually are making funny noises or leaking. or in some harsh cases seizure. on the other hand your thermostat you;'ll probably have to take a look at it and determine that. but they are usually stuck open or closed or even partially. If your having a heating problem your first look maybe your thermostat not allowing the coolant to circulate. Sometimes people don't even go through the hassle of diagnosing a bad thermostat , they just go and purchase a new one becuase they are usually so very inexpensive. and don't forget your engine coolant temperature sensor, those three items work together.

No problem.

Unforunately if flushing the core does not work then you may have to replace the heater core. However this sounds like the core is just slightly clogged so a good flush might fix your problem!

i will book it in to a rad shop so i will know it getts a proper flush....ty

i have a problem with the van where it is over heating and its blowing out cool air.please help

check for coolant leak
add as needed
check intake manifold gasket


need manual CHECK IT @
https://www.2carpros.com/kpages/auto_repair_manuals.htm
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N0 heat at idle,chevy venture 2003, heat only when driving vehicle, no heat at warm up , no matter how long I warm her up.

Does the vehicle reach normal operating temp? Are the heater hoses hot. Does the blower motor work?

You may have a partially clogged heater core. You can try removing both heater hoses and pressure flush it with a garden hose.
Make sure the sure the system is topped off with coolant when your finished.

Engine heats up fine turn fan on and only blows cold air.

check coolant level for being full then try pulling HVAC fuse inside car for sixty seconds with key on then reinstall might reset blend door actuator.

Have a 02 venture with spuratic heat in front, Little when idoling pretty hot when running hard or reving engine. Also no heat in rear no diffrence between AC or heat just strong cold air. Lines to rear are both Hot
I replaced T-Stat , next day flushed system, with rear hoses off also seemed to flush with power no water trickling. Also the front fan speed dial only works on 1,2,4(blower resistor bad) I just can't belive the Intake gasket is causing this condition. Please explain or a fix for this common problem.

Needing the rpms up to get heat from the front is usually a partially plugged heater core.You will want to be careful if you decide to flush this out yourself using a hose, it isnt that easy to replace it if it pops from too much pressure. The Dexcool (coolant) used in those vehicles would clog heater cores, fairly common issue as long as the cooling system is full with no air pockets.The rear heater could be the blend door (hot/cold door) not working if you have both hoses hot, that usually means the hot coolant is flowing in and out.You should hear a difference in sound in the rear assembly when going from hot to cold, if not the door isnt working. You will have to remove the interior panels to access the assembly to visually see why it isnt working.

On the first cold day of winter (below freezing) our van temp gauge pegged out into the redzone and the warning light came on. However, the heater was not blowing warm air at all.

We took it in to a local shop and they could not repeat the problem. Carbon dioxide test came back negative. The shop did not want to change the thermostat because they had no idea what was wrong with it.

I picked the van up after work on a Friday and it touched the redzone on the way home. I had read something about there being two relays for the fans, so I tried turning the air on to override one of the relays and the temp started to drop immediately. However, still no heater. Monday got up early to fill the van up and check it out, it never overheated on the way to the gas station, but came very close. Still no heater.

I can find a lot of complaints about Chevy Ventures like this on the interent, but no one has posted a solution.

Okay, this can be caused by several things. First, make sure the coolant is full. Also, let me know if the car overheats when you are at highway speed. Next, with the engine running, hot, and the heater on high, feel both heater core hoses. Both should be hot. Finally, check to make sure there is no coolant getting into the oil.

As far as the fan, does at least one turn on when you overheat?

Have you had to add coolant?

Joe

Coolant is full. No coolant in oil. Will have to check the rest after work today. Although the shop I took it to told me the fans were working. But, this could be an intermittent problem.

However, on the way to work today (outside temp 41 deg F) everything seemed to work fine. Even the heater.

This is after this morning going and filling it up at a gas station and having some problems. See previous posting. I am not sure what the outside temp was this morning, but the temp is supposed to drop all day.

Van has worked well the last few times I drove it, until this morning. Just as I pulled into work (roughly a 12 to 15 minute drive) the temperature gauge started into the red zone. And I had no heat coming out of the vents. I parked the van and opened the hood, both fans were working. I grabbed the upper radiator hose and it was still cool. I squeezed it a few times then shut the hood in disgust. I went to turn the van off and now the temp gauge is reading normal. I opened the hood again and touched the upper hose and it was starting to get warm. The outside temp is 17 deg F.

What is going on with this thing? Can a thermostat work intermittently?

Believe it or not, yes it could be the thermostat. Infact, based on your description, it sounds like it may be sticking shut. I would try replacing it to see if that helps.

Let me know what you find and thanks for using 2carpros.com

Joe

Here is what I have done and it seems to have worked:
I drained some of the fluid out of the radiator and added straight antifreeze. I then drove it to work and on the way to work it started to climb in temperature (but never overheated).

It reached about 3/4 of the way to overheating and then dropped back to normal operating zone. It has worked fine ever since.

I noticed it was overheating only on really cold days, so I figured the antifreeze to water ratio must be off.

If anything changes in the next few days, I will updated this thread.

The van has gone through many recent repairs to fix this problem along with other symptoms, in the following order : - Changed thermostat > tuned vehincle > Changed water pump > changed thermostat > flushed radiator > flushed heater core > changed head gasket > replaced overflow hoses > performed coolant flush & replacement.

Still, the following symptoms exist :
- Temperature guage shows cold (1/3mark) on higher RPMs ,and is in middle when idling
- engine & vehicle vibrate quite a bit on idle
- normal heat from heater when on idle but drops to luke warm at higher speeds/rpms.
- fuel efficiency has reduced from 20+ mpg to 17-18 mpg.
- no other warning lights/messages visible

During cold days my feet almost got a frostbite.. please advise. Thank you!

have the vehicle scanned, Have a compression check done. What it sounds like to me is that something in the compression, or electrical problem, so it is not firing on all cylinders.

If that seems to help, I would recommend draining it all out and replacing it with a 50/50 mixture of coolant and water. Also, if the vehicle came with dexcool coolant, make sure you dont mix it with any other type of coolant unless it is a universal coolant GO-5 that can be mixed with dexcool.

Also, when you remove the coolant, replace the thermostat. If it around a 5.00 part and it may still be the cause of the problem.

Let me know how things work out for you. THanks for using 2carpros.com and I wish both you and your family a safe and happy holiday.

Joe

Are you suggesting a engine compression or cooling system compression test? I had the latter done with no issues. Engine runs powerful and with no misfires (if it were not firing all cylinders I would get a check engine light but I don't see any such lights). It only vibrates when on idle. Anything else to consider before going ahead with the engine compression test and other repairs??

try this, get some engine cleaner, the one you put in the gas, it will clean out the fuel line and injectors. that should help it run better. I re read your post to see if i missed anything. With the temp guage going up half way when ideling and going down to 1/3 when moving, my first guess would be try another thermastat. With it ideling the system does not cool off as much. Simular to overheating when sitting ideling in really hot weather. but when you move then the fluid will cool faster. A defective thermastat would produce the same symptons.

Try changing your cabin filters. I had the same issue, and I found out about these cabin filters, and so I changed them and what a difference

I am really hoping you can help me figure out what is going on in my engine. Ok here is the story. We bought this van used with 152000 miles on it. Around 151000 miles on it we replaced the intake gaskets because they went bad. At 152000 even the head gaskets blew and it was cheaper to put an used engine in it instead of the repair. We purchased a used engine with 87000 miles on it. We have since put 5000 miles on it. Well while driving home today (on the freeway) the temp. gauge shot up to the red and I had not heat. I limped it home. While driving the temp went down to a 1/4 on the gauge. Still no heat. The coolant is backed up in the resevoir. I am able to drive it for about 1.5 to 2 miles before it gets hot and then it goes down to 1/2 and then back up. Still no heat. PLEASE HELP!!!

There has to be a loss of coolant occuring somewhere. Have the cooling system pressure tested. Also do a block test to see if there are exhaust gasses in the cooling system.

There's a TON of people that have this exact same problem with Chevy Ventures. I was one of them... It is a MAJOR PAIN IN THE REAR to get the air out of the coolant system! Sounds like the problem.. also, b careful cuz ive been told that due to the aluminum heads, they are very prone to blown head gaskets, warping etc. after even only one overheat... There is (actually two) bleeder screws on the coolant system. I use the one on the passenger side of the vehicle because its higher and better to let out extra air... Its located about ten inches to the left of the oil fill cap. It has a hex head (cant remember the size) and its very simple to bleed the air out by unscrewing it a few turns and bleed until coolant streams out. This process took me like two days of repeating until finally my temp gauge and everything is back to normal...

The answer I got from Niz76 was awesome to stop my overheating of my engine and get my heater to blow hot air in my 1997 Chevy venture. it took me 20 minutes to pop the rad cap, release the bleeder nut on the left hand side and start the van and squeeze the hoses on both sides while the van was running. As soon as the antifreeze started running out of the bleeder nut hole, I tightened the bleeder nut and put the rad cap back on tight and took the van for a boot around the block a few times. Problem fixed, no overheating,and awesome hot heat.... THANKYOU

no heat, temp guage spikes and falls, replaced thermostat, burped the system(@ a garage)
checked all relays and fuses

TWO WORDS...

HEAD....GASKET TONS of articles on this and it's UNFORTUNATELY a COMMON PROBLEM...its what happens when you take an aluminum head and place a rubber gasket between it and a cast iron block...

Before I got the answer from this site , my 1997 Chevy Venture heat gauge also would spike to red line hot and then drop down to cold and then back up to super hot and the heater was blowing cold air and I couldn't figure it out , what was causing the problem. I finally found that the small spout just under the rad cap that connects the overflow hose to the plastic overflow tank , was cracked on the bottom side and was spitting antifreeze onto the ground. As the engine would heat up and des pence my antifreeze out this crack it created air blockage in the whole line. I had to replace the rad as JB weld wasn't able to repair the crack. Once I got everything all back together, I still ran into the problem of engine overheating and no hot air coming from my heater because of the air getting into my system until I bled the line with rad cap off also and removing the bleeder bolt until antifreeze flowed out of hole and then I put the cap back on and the bleeder nut back on and tightened down and all was great

Has a new thermostat. No external coolant leaks. Could it be a blown head gasket?

Have it block and pressure tested-do the block first to pinpoint a combustion leaking into the cooling system or a gas analyzer to sniff for hydrocarbons at the radiator fill neck.

Pressure test: do not do a pressure test if there's leakage at the headgasket this might cause coolant into the cylinders and lock it up or bend a connecting rod if cranked thereafter. The headgasket should be repaired before doing the pressure test.

If the block and pressure test passes check the following: Thermostat,Pressure test the Rad. cap,Clogged radiator,Fan clutch,Radiator electrical fan,collaspe hoses,water pump.