HEATER PROBLEM NEED HELP! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GABE310 · 03-29-2002, 12:49 AM

When I turn my heater on the fan runs really slow and blows weak.But when I put direct power to the blower motor it blows strong. Could someone tell how I can fix it to blow stronger? Thanks inadvance for your help.

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72 CHEVY 4X4 BLAZER
69 CHEVY SWB
95 HARLEY DAVIDSON NOSTALGIA

[This message has been edited by GABE310 (edited March 28, 2002).]

RussTburb · 03-29-2002, 12:58 AM

Sounds to me like you either have to much resistance in the wires going to the fan motor. If you have a voltmeter backprobe the wires to the fan and see what your voltage is if it is not battery voltage with the fan on high you have either a bad blower motor resistor or wires going to the fan.
Hope this helps. You can use a 12volt test light and if it glows only dim then same problem. Let me know what you find okay?

Zurbo · 03-29-2002, 01:24 AM

Mine done that and I had to replace the fan switch. It had some bad (worn out) contacts and was not kicking in the high speed relay.

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Zurbo's Chevy - 1972 Black/White Cheyenne Super. 400 Big Block /THD 400, factory air and tilt.
My other Chevy - 1998 Camaro SS

jostrans68 · 03-29-2002, 01:35 AM

on the heater box there is a reostat (sp) that controls this it is bad

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68 c20 in progress 327 TH400 tach dash Disc Brakes and soon 3.90 rear gears.. have many new parts now just need the time..... Sound Familar
Tacoma Wa. The Rain capitol of the USA

Blazer1970 · 03-29-2002, 12:40 PM

It is most likely the switch. If the resistor goes bad, the fan will usually only work on high, and not on the lower speeds.

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Tim

03-29-2002, 12:49 AM	#1
GABE310 Registered User Join Date: Mar 2001 Location: SOUTHERN,CA Posts: 429	HEATER PROBLEM NEED HELP! When I turn my heater on the fan runs really slow and blows weak.But when I put direct power to the blower motor it blows strong. Could someone tell how I can fix it to blow stronger? Thanks inadvance for your help. ------------------ 72 CHEVY 4X4 BLAZER 69 CHEVY SWB 95 HARLEY DAVIDSON NOSTALGIA [This message has been edited by GABE310 (edited March 28, 2002).] __________________ 68 CHEVY SWB 95 HARLEY DAVIDSON NOSTALGIA 68 CAMARO CONV 65 CHEVELLE CONV 39 CHEVY CABOVER

03-29-2002, 12:58 AM	#2
RussTburb Registered User Join Date: Mar 2002 Location: Blaine,Wa. U.S.A Posts: 261	Sounds to me like you either have to much resistance in the wires going to the fan motor. If you have a voltmeter backprobe the wires to the fan and see what your voltage is if it is not battery voltage with the fan on high you have either a bad blower motor resistor or wires going to the fan. Hope this helps. You can use a 12volt test light and if it glows only dim then same problem. Let me know what you find okay? __________________ "Red-heads not war-heads, Blondes, not bombs, Brunettes, not fighter jets!" Fligh of the Choncords 72 burb 3/4 ton 2wd 06 2500 suburban 8.1L 4x4 84 chev 4x4 diesel 96 Geo Metro with the 4cylbb, lol! Almost 300k just won't die! 89 Honda Civic, runs on the smell of an oily rag! 2008 Aerolite 26qs Travel Trailer (aka "THE BARN")

03-29-2002, 01:24 AM	#3
Zurbo Registered User Join Date: May 2001 Location: Bel Aire, Kansas, USA Posts: 186	Mine done that and I had to replace the fan switch. It had some bad (worn out) contacts and was not kicking in the high speed relay. ------------------ Zurbo's Chevy - 1972 Black/White Cheyenne Super. 400 Big Block /THD 400, factory air and tilt. My other Chevy - 1998 Camaro SS __________________ Zurbo's Chevy - 1972 Black/White Cheyenne Super. 402 Big Block /THD 400, factory air and tilt. My other Chevy - 1998 Camaro SS

03-29-2002, 01:35 AM	#4
jostrans68 Jostrans68 Join Date: Mar 2001 Location: Bloomington indiana Posts: 1,182	on the heater box there is a reostat (sp) that controls this it is bad ------------------ 68 c20 in progress 327 TH400 tach dash Disc Brakes and soon 3.90 rear gears.. have many new parts now just need the time..... Sound Familar Tacoma Wa. The Rain capitol of the USA __________________ [CGTW Member former 67-72 now with a 96 silverado

03-29-2002, 12:40 PM	#5
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,510	It is most likely the switch. If the resistor goes bad, the fan will usually only work on high, and not on the lower speeds. ------------------ Tim __________________ Tim



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