I have no heat. Started awhile back. Changed the thermostate a couple months ago. The blower worked fine it just blew out cold air. To start I have no hose, I'm renting this house and have no hose hook up. I took the heater hoses off and blew the heater core out with my air compressor and blew all kinds of chunks out of there.But, since I blew out the heater core I have no blower. There is nothing comming out of the vents at all. I turnedit to hot and cold ac and heat with no air blowing at all. When I switch the diferent vents i can hear it switch inside but no blower. While running the car the temp got all the way up to thewhite line after the 210 mark, what is that 225 - 230or something? Then the thermostate must have opened because the tamp went to normal.

1. Why dont I have a blower now and what can I check to fix this.
2. Why did the temp get so high

I can change the thermostat again thats fine but that still wont help not having any air blowing through the vents. HELP

Just came in, I checked the hvac fuse and thats fine. I checked to make sure all the harnesses are tight and I didn't knock them loose.

The last time I came in I left the car running with the radiator cap off and there was coolant everywhere. I added a gallon of water just to fill the radiator back up. Still no air blowing from the vents.

I went out and bought a new thermostat. I installed that and added fluid and tried to get all of the air out. That seemd to work for temp. I took it for a ride and the temp staid normal just below the 210 mark plus I left it running for awhile also. I still have no blower. When I was blowing out the heater core with the compressor i blew a fuse in the house. I'm thinking that either the fuse blowing made me blow a resistor or blower motor from my air nozzle touching the matal of the car. I didn't dis connect the battery. I'm not sure if this can happen or not but who knows. I guess it's onto testing all of the connections.

I'm not very good at using the multimeter but I tested the harness that connects directly to the blower motor. I got 14 volts I believe. I couldn't probe it while connected to the motor and turn the switch to see if it reads diferent on other settings because by this time it was dark, time to go in.

Today I connected two wires right from the battery to the blower motor. It started up and stayed running, so that tells me that the blower motor is good. I also checked the voltage at the connector for the blower motor and on the posotive side I get around 14 volts and on the neg terminal I get a - number. So i assume that since I get power to the connector itself then the switch, resistor, fuses, and the other part(lost it in my head) are all fine. If any of these parts were bad then I wouldn't get power to the connector at the motor. So I believe if I cut the connector off at the blower motor and connect it two female ends then it should work. I shouldn't be getting a number at all when I test the neg terminal while the connector isn't conected to the motor. Is this correct. Can anyone help me with this?

 

Greed, please add your vehicle information into your signature and attach it to your posts so others do not have to go looking for it. From other posts, I can see that you have a 2004 4wd blazer.

From the sounds of it, the blower motor is not working at all. Can you hear it moving? If not, there are a few different components in the loop before power gets to the motor itself.

The blower motor relay should be located towards the center of the firewall near the HVAC housing. Then there is the blower motor resistor pack which regulates the speed of the blower motor.

I would first start off by having the key in the RUN position, fan speed *** to HIGH, and then disconnect the blower motor and test the voltage across the connector. You should get battery voltage. If you do, the blower motor is bad.

If you do not get power at the blower motor even on HIGH speed and the HVAC fuse is good, then the relay is most likely at fault.

The blower motor resistor drops the voltage to allow for the lower speeds so diagnosis starts with HIGH speed.

 

Bump

 

Bump with no update...[&o] Did you try anything suggested? If so, what was the outcome? From the looks of it, you are looking for someone to pull out the magic bullet for you.

 

At the time I bumped this I didn't see any replies, maybe I missed yours. I updated my original post several times with my latest findings at the bottom. Also last week sometime I added a pic of my blazer as an avatar and in the sig part at the bottom I added the truck info.

A magic bullet, Nope. I'm just not good with the electrical stuff at all. Not good with a multimeter either. I was simply looking for a little guidence. Maybe just a little reassurance I was headed in the right direction. You can read my past updates in the first post I made for this thread. Nw with all that said, since I know the blower motor itself is not bad and the other components are not dead either because I have voltage to the blower motor harness. and when I jumped the blower motor straight from the battery it came on and stayed on. So today I cut of the harness to the blower motor and hooked it up with two female insukated connectors and still nothing so I then left the power wire hooked to the blower motor and left the ground wire off. I then hooked a ground from the chassis to the ground terminal of the blower and it came on and worked perfectly. So I now know my problem is a bad ground somewhere. Although I will have to get a new resister because my #4 position barely blowes any air. while 1 2 and 3 work great. I was getting 14 volts to the posotive terminal and the negative terminal was getting almost the same voltage but it was jumping all over the place telling me my ground was bad somewhere or there is something shorting out. If I cant find the problem then I will temporarily hook the wire from a grounded source right to the blower motor so I atleast have heat until I can figure it out. Just figured I would post my progress.

 

Ok I did some more stuff. After all the other tests, I figured out that something had to be backfeeding through the negative wire on the blower motor because I was getting voltage at both the posotive and the negative wires for the blower motor. I cut the harness from the blower motor. I left the posotive wire connected to the blower motor and I ran a ground from the negative terminal to the ground bolt by the resistor and it worked great. So when I blew the heater core out with the compressor it must have worked.

It was raining so I went to take it for a ride and tried my wipers(earlier post about non working wipers still wasn't fixed) and the wipers went back and forth two times then stopped. when they went off my blower went off also, I lost the blower on settings 2 and 4. I got back and started to fiddle with the wiper motor and noticed that the ground cable bolted to the firewall right next to the wiper motor on the fire wall was way loose (nut almost falling off) so I tightened that ground cable and retried the wipers. The wipers worked flawlessly and I had had heat blowing from all 4 settings even the 2 and 4 that just did not work. I then decided to reconnect the blower motor harness to see if it would work and that also worked flawlessly. This bad ground fixed my wipers and my blower motor.

moral of the story .... before all else, check your ground connections. Oh yea, my wife had to go to the doctors today and called me to complain that it's two hot in the blazer now. Thank You swartlkk for your help. It is much appriciated.

 

Hahah too hot...gotta love it. Glad you got it figured out!

 

Glad to help! Thank you for the follow up!!