no heat

johnboi25 · 11-20-2008, 04:26 PM

I am trying to figure out why my heat isn't working my blower comes on but doesn't get hot, also my a/c button the light doesn't come on neither does the other light for circulation i guess. my vehicle is a 98 chevy silverado Z71 5.7 and im freezing

**SABL** · 11-21-2008, 06:29 AM

Hi jonboi25,
Just to try to make this easier start here:
98 chevy silverado c1500 heater issues

See if this helps and let us know,
SABL

Marb750 · 11-28-2008, 03:26 PM

Yes, coolant level is the best place to start (start easy and work your way to the more difficult stuff

).

If that's not the issue, you may have something else going on, especially since some of the buttons aren't responding - or at least the lights. A little info:
According to AllData, the heater control valve opens and closes to allow coolant to circulate through the heater core. The valve itself is vacuum operated. But the actual dash unit is electronic and controls vacuum going to the valve. The blend door inside the heater box controls how much warm air from the heater core is blown out the vents - the blend door is electric-operated.

So, what does this mean? It means that you *may* have one of several different issues going on.

So, first off check coolant level. Then check all your fuses. If that gets you nowhere, check for any signs of disconnected or damaged vacuum lines under the hood. Do you live in an area with rodents? Rats, mice and squirrels LOVE to chew on vacuum lines and insulated wiring. I don't know why, but I've seen it MANY times...

I'm also new to this site, so it may be a while before I get back to this thread, just thought I'd add my $.02.

-Marb

olemiss74 · 12-10-2008, 08:17 PM

Have you looked at the blend door actuator and see if it is working? just a thought.

**mack1** · 12-12-2008, 11:18 AM

Hi John and welcome to TSF,

Sounds like no circulation of water through the heater core. Did you feel of the two heater hoses to see if they were both hot? If one is hot the other not, there is little or no water through the core and the problem is either a control valve not opening or the core stopped up. Marb750 has given you some insight on the controls part, but for the stopped up part, remove both the hoses at the engine and use your garden hose to flush out the core.

Hope this helps,
Mack1

**SABL** · 12-12-2008, 01:13 PM

Hiya Mack1

Hope all is well down there and you're ready for the holidays!!

Aren't heater cores fun

I still haven't gotten to mine...been putting it off. I love

those quick connects... now if somebody could invent quick DISconnects I would be much happier. I have resigned myself to the fact that I am going to destroy my heater core (not worth salvaging and have replacement in hand) to access the connections. Replacement connectors are available but I am tightwad.

Yep, the tubes in a heater core are quite small (conductance issue) and can become clogged (blocked) very easy. A good flush can do wonders for the comfort of driver and passengers.

11-20-2008, 04:26 PM	#1 (permalink)
johnboi25 Registered User Join Date: Nov 2008 Posts: 1 OS: win2000	no heat I am trying to figure out why my heat isn't working my blower comes on but doesn't get hot, also my a/c button the light doesn't come on neither does the other light for circulation i guess. my vehicle is a 98 chevy silverado Z71 5.7 and im freezing

11-21-2008, 06:29 AM	#2 (permalink)
SABL Moderator Relaxation Room Join Date: Jul 2008 Location: Galena, Ohio Posts: 1,229 OS: WinXP SP3	Re: no heat Hi jonboi25, Just to try to make this easier start here: 98 chevy silverado c1500 heater issues See if this helps and let us know, SABL

11-28-2008, 03:26 PM	#3 (permalink)
Marb750 Registered User Join Date: Nov 2008 Posts: 33 OS: XP SP3	Re: no heat Yes, coolant level is the best place to start (start easy and work your way to the more difficult stuff ). If that's not the issue, you may have something else going on, especially since some of the buttons aren't responding - or at least the lights. A little info: According to AllData, the heater control valve opens and closes to allow coolant to circulate through the heater core. The valve itself is vacuum operated. But the actual dash unit is electronic and controls vacuum going to the valve. The blend door inside the heater box controls how much warm air from the heater core is blown out the vents - the blend door is electric-operated. So, what does this mean? It means that you may have one of several different issues going on. So, first off check coolant level. Then check all your fuses. If that gets you nowhere, check for any signs of disconnected or damaged vacuum lines under the hood. Do you live in an area with rodents? Rats, mice and squirrels LOVE to chew on vacuum lines and insulated wiring. I don't know why, but I've seen it MANY times... I'm also new to this site, so it may be a while before I get back to this thread, just thought I'd add my $.02. -Marb

12-10-2008, 08:17 PM	#4 (permalink)
olemiss74 Registered User Join Date: Dec 2008 Location: Oxford, Ms. Posts: 24 OS: windows vista	Re: no heat Have you looked at the blend door actuator and see if it is working? just a thought.

12-12-2008, 11:18 AM	#5 (permalink)
mack1 TSF Articles Team Join Date: Nov 2007 Location: Texarkana, Texas Posts: 1,245 OS: xp sp3 My System	Re: no heat Hi John and welcome to TSF, Sounds like no circulation of water through the heater core. Did you feel of the two heater hoses to see if they were both hot? If one is hot the other not, there is little or no water through the core and the problem is either a control valve not opening or the core stopped up. Marb750 has given you some insight on the controls part, but for the stopped up part, remove both the hoses at the engine and use your garden hose to flush out the core. Hope this helps, Mack1 __________________ "If you like yourself others will like you also" me "Don't drink downstream from the herd" Will Rogers Submit New Articles Here

12-12-2008, 01:13 PM	#6 (permalink)
SABL Moderator Relaxation Room Join Date: Jul 2008 Location: Galena, Ohio Posts: 1,229 OS: WinXP SP3	Re: no heat Hiya Mack1 Hope all is well down there and you're ready for the holidays!! Aren't heater cores fun I still haven't gotten to mine...been putting it off. I love those quick connects... now if somebody could invent quick DISconnects I would be much happier. I have resigned myself to the fact that I am going to destroy my heater core (not worth salvaging and have replacement in hand) to access the connections. Replacement connectors are available but I am tightwad. Yep, the tubes in a heater core are quite small (conductance issue) and can become clogged (blocked) very easy. A good flush can do wonders for the comfort of driver and passengers.