Poor Heat, Not Sure Where to Start - Diesel Place : Chevrolet and GMC Diesel Truck Forums
 
Home Forum Market Place Garage Lounge (0) Tuning Library DTC Tool Register Vendors
Go Back   Diesel Place : Chevrolet and GMC Diesel Truck Forums > GM Diesel Engines > 6.5L Diesel Engine
Register FAQ Forum Rules My Replies My Threads Mark Forums Read Auto EscrowAuto LoansInsurance

DieselPlace.com is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools
Old 01-01-2013, 04:08 PM   #1 (permalink)
GbByChubsy
Diesel Specialist
 
GbByChubsy's Avatar
 
Join Date: Sep 2010
Location: Dublin, Ohio
Posts: 509
iTrader Score: 0 reviews

The Suburban Club Member

Poor Heat, Not Sure Where to Start

Well, I have poor hear and air flow from the both rear and front vents. Not blowing hard enough and not nearly warm enough. Blower motor still runs but I believe is starting to die, still more air flow should be coming regardless.

Not sure where to start, don't want to rip off the dash for no reason. Need some diagnostic help/steps
__________________
1999 Chevy Suburban K2500 6.5L Turbo Diesel "F" Vin
Factory Build Date: October 1999
Currently running like a world CHAMP! 152K
New Stanadyne PMD with cooler, mounted under front bumper Rebuilt Heads from Surefire New Bosch Duratherms Glow Plugs New Batteries, K&N Air Filter and Fuel Filter, Lift Pump,
Map Sensor, Crankshaft Sensor and a Completely Rebuilt Injection Pump from Columbus Diesel Supply
Mobil 1 5W-40 Tuebo Diesel Oil, K&N Oil Filter
285/70 R17 BF Goodrich All-Terrain
17" Hummer H2 Chrome Wheels
New A/C compressor, drier and O-Tube
New Diamond Eye Exhaust, High Flow Muffler
New HD Tow Mirrors with Turn Markers
New Brake Pads, Rotors and Calipers
Offline  
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 01-01-2013, 04:36 PM   #2 (permalink)
Graplr
Diesel Specialist
 
Graplr's Avatar
 
Join Date: Aug 2009
Location: Stillwater, Minnesota
Posts: 765
iTrader Score: 0 reviews

Minnesota/Western Wisconsin DP Club Member

If the blower motors aren't working, I'd start by pulling them and/or applying 12 volts directly to see how they run.

How is your engine temperature? How long does it take to warm up (the engine)?
__________________
Ryan
1994 Chev Suburban K2500 6.5 244k miles
-Diamond Eye Exhaust with muffler & 2.5" FloPro Crossover Pipe
-LubSpec Oil Cooler Kit
-Webasto Diesel Coolant Heater w/Remote Start
-Remote PMD on Heat Sync in bumper, HID Headlights w/new lenses
-Newer IP, New Bosch Injectors, New Bosch Duraterm Glow Plugs, Newer Radiator
-PYO Aluminum Wheels, Bridgestone Dueller II A/T tires
-Boost, Fuel Pressure, EGT Gauges, K47 intake w/Amsoil EaA 112 Air Filter
-Rebuilt Transmission @ 227k miles
-LP Relay Mod, High Idle Switch Mod, Glow Plug Override Mod, Battery Terminal Mod
-New OPS, Batteries, Brakes, Starter, Alternator, Fuel Lines, Lift Pump, Vacuum Pump
-GMTD Scan Tech
-599 Block from the factory
Offline   Reply With Quote Quick reply to this message
Old 01-01-2013, 04:47 PM   #3 (permalink)
PrivatePilot
Administrator
Resident Coffee Addict
 
PrivatePilot's Avatar
 
Join Date: Jun 2008
Location: Near The Coffee Maker
Posts: 15,118
iTrader Score: 0 reviews

Ontario Diesel Place Chapter Member

Poor airflow is usually a result of one of the flapper / distribution flaps not working properly within the HVAC box. Unfortunately, it's behind the dash and can be a miserable thing to work on.

Do you have more air flow in some positions (dash vents, floor, defrost) vs others, or is it a universally bad flow across all of them?

Can you hear the blower motor speed and up and slow down when you change positions on the control? Does it appear to be working at full speed on the "High" setting?

And as Graplr asks, what is your engine temperature getting up to? Lack of heat is often a result of a thermostat that is stuck open, so the engine never actually heats up properly.
__________________


Mark - Courtice, Ontario, Canada.
'97 C3500 Crew Cab Long Box Dually 6.5 Turbo Diesel.
Rebuilt with Navistar 506 block spring 2012
Special thanks to Racer55 and WhiteK2500 for their invaluable assistance!
Commercial OTR Driver Since '95

Find my list of reference information HERE
New members, please introduce yourself HERE
Offline   Reply With Quote Quick reply to this message
Old 01-01-2013, 05:57 PM   #4 (permalink)
57diesel
Diesel Master
 
Join Date: Mar 2012
Location: St. Paul/Minneapolis MN USA
Posts: 1,968
iTrader Score: 0 reviews

Pilot asks good questions as far as does the air move to the various vents when you turn the dial. That era was terrible for the quality of all the components related to the duct work. The motors fail which depending on which one may not be too bad to replace. The air doors in the ducts also fail and the doors are an extra pain to work on. On both my 96 and 97 the mode doors were messed up. Its a set of 3 that run off one motor. One of them falls off its pivot and jams up the rest so you pretty much get no air out the left side vents and it does not really change much, it just blows out most of the vents most of the time. I did a write up on the repairs to my 96 in the interior section.

As far as the hotness of the heat goes I had a flush done on mine last week and it really helped. Mine would only blow hot when going down the freeway. Around the city and at idle it was barely warm. Don't know if its a factor or not but mine still had dexcool in it.
__________________
96 Burb K25 3.42's 320K miles so far, told its all original, front bumper grey pmd otherwise stock, close race between engine wearing out or body completely rust out.
95 Burb K25 3.73's 250K miles, looks to have been rebuilt at least once, stock, bad rust, 8' western plow.
81 Buick Riviera with the infamous Olds 5.7 diesel still going strong.
13 VW Jetta Sport Wagon TDI of course, does low 40's around town and can see 50's on the highway.
Online   Reply With Quote Quick reply to this message
Old 01-01-2013, 09:51 PM   #5 (permalink)
tookielee
Diesel Specialist
 
tookielee's Avatar
 
Join Date: Dec 2007
Location: Port Vincent, Louisiana (near Baton Rouge)
Posts: 758
iTrader Score: 0 reviews

Also, the fins get clogged, and won't let air flow thru, may need to wash them too.
__________________
Tookie LeBlanc
Current DD: 2012 VW Jetta TDI

Newest truck: (11/2011 - 3/2013, Sold!)
2009 Toyota Tacoma, TRD sport 4X4 crewcab
New truck: (December 2010 - October 2011, SOLD!)
2004 Chevy 2500HD, LB7, bone stock for now Hypertech III, K&N
cold air, Cooper Discoverer HTs, Rhino liner...

Old Truck: (2003 - 2010)
1997 GMC Sierra X/C longbed, 6.5 / 4L80E 240,000 + miles, original IP, 3rd PMD, (now remote mounted Dipaco)
deleted vac pump and home made TM, ceramic pads, Outlaw rims with new Cooper ATRs
Offline   Reply With Quote Quick reply to this message
Old 01-01-2013, 09:58 PM   #6 (permalink)
JMJNet
Diesel Laureate
 
JMJNet's Avatar
 
Join Date: Feb 2006
Location: Richardson, TX
Posts: 12,376
iTrader Score: 0 reviews

The Suburban Club Member

T-stat?
__________________
1995 GMC Suburban:
PMD in Bumper
4" Warpspeed Exhaust
KD LP/OPS Harness
Bosch Duraterm GP
Heath Turbo-Master
Chevron's XLP Diesel Additive
Offline   Reply With Quote Quick reply to this message
Old 01-01-2013, 10:02 PM   #7 (permalink)
PrivatePilot
Administrator
Resident Coffee Addict
 
PrivatePilot's Avatar
 
Join Date: Jun 2008
Location: Near The Coffee Maker
Posts: 15,118
iTrader Score: 0 reviews

Ontario Diesel Place Chapter Member

Quote:
Originally Posted by tookielee View Post
Also, the fins get clogged, and won't let air flow thru, may need to wash them too.
That was on my mind, hence my question about airflow being consistently poor across all settings, or just one.

I had this happen on an old car of mine - the AC evaporator leaked and the oil collected garbage to the point where no air could get through.
__________________


Mark - Courtice, Ontario, Canada.
'97 C3500 Crew Cab Long Box Dually 6.5 Turbo Diesel.
Rebuilt with Navistar 506 block spring 2012
Special thanks to Racer55 and WhiteK2500 for their invaluable assistance!
Commercial OTR Driver Since '95

Find my list of reference information HERE
New members, please introduce yourself HERE
Offline   Reply With Quote Quick reply to this message
Old 01-02-2013, 08:26 AM   #8 (permalink)
GbByChubsy
Diesel Specialist
 
GbByChubsy's Avatar
 
Join Date: Sep 2010
Location: Dublin, Ohio
Posts: 509
iTrader Score: 0 reviews

The Suburban Club Member

Air flow does changes properly based on the controls of high down to low. The temp is fine, around 185-190 consistently.

Also as someone noted above, I have poor heat at idle. When I am at a traffic light, the flow seems to reduce a bit, and it does not blow hot. At normal speeds it is fine, but at stops it does this.

More over, air flow is consistent at all selections, floor, defrost ect.
__________________
1999 Chevy Suburban K2500 6.5L Turbo Diesel "F" Vin
Factory Build Date: October 1999
Currently running like a world CHAMP! 152K
New Stanadyne PMD with cooler, mounted under front bumper Rebuilt Heads from Surefire New Bosch Duratherms Glow Plugs New Batteries, K&N Air Filter and Fuel Filter, Lift Pump,
Map Sensor, Crankshaft Sensor and a Completely Rebuilt Injection Pump from Columbus Diesel Supply
Mobil 1 5W-40 Tuebo Diesel Oil, K&N Oil Filter
285/70 R17 BF Goodrich All-Terrain
17" Hummer H2 Chrome Wheels
New A/C compressor, drier and O-Tube
New Diamond Eye Exhaust, High Flow Muffler
New HD Tow Mirrors with Turn Markers
New Brake Pads, Rotors and Calipers
Offline   Reply With Quote Quick reply to this message
Old 01-02-2013, 10:08 AM   #9 (permalink)
Graplr
Diesel Specialist
 
Graplr's Avatar
 
Join Date: Aug 2009
Location: Stillwater, Minnesota
Posts: 765
iTrader Score: 0 reviews

Minnesota/Western Wisconsin DP Club Member

Quote:
Originally Posted by GbByChubsy View Post
Air flow does changes properly based on the controls of high down to low. The temp is fine, around 185-190 consistently.

Also as someone noted above, I have poor heat at idle. When I am at a traffic light, the flow seems to reduce a bit, and it does not blow hot. At normal speeds it is fine, but at stops it does this.

More over, air flow is consistent at all selections, floor, defrost ect.
That does sound like either a blower/voltage issue or a block in the heater core fins.

A few weeks ago someone was posting about the same issue as yours. That is poor heat around town or at idle but okay on the highway. He did a coolant flush and he stated that solved his issue.
__________________
Ryan
1994 Chev Suburban K2500 6.5 244k miles
-Diamond Eye Exhaust with muffler & 2.5" FloPro Crossover Pipe
-LubSpec Oil Cooler Kit
-Webasto Diesel Coolant Heater w/Remote Start
-Remote PMD on Heat Sync in bumper, HID Headlights w/new lenses
-Newer IP, New Bosch Injectors, New Bosch Duraterm Glow Plugs, Newer Radiator
-PYO Aluminum Wheels, Bridgestone Dueller II A/T tires
-Boost, Fuel Pressure, EGT Gauges, K47 intake w/Amsoil EaA 112 Air Filter
-Rebuilt Transmission @ 227k miles
-LP Relay Mod, High Idle Switch Mod, Glow Plug Override Mod, Battery Terminal Mod
-New OPS, Batteries, Brakes, Starter, Alternator, Fuel Lines, Lift Pump, Vacuum Pump
-GMTD Scan Tech
-599 Block from the factory

Last edited by Graplr; 01-02-2013 at 10:09 AM.
Offline   Reply With Quote Quick reply to this message
Old 01-02-2013, 10:08 AM   #10 (permalink)
57diesel
Diesel Master
 
Join Date: Mar 2012
Location: St. Paul/Minneapolis MN USA
Posts: 1,968
iTrader Score: 0 reviews

My temp gauge always held steady. My theory was that there was enough internal clogging in the heater cores that you needed the water pump to be spinning a bit faster to get the pressure to circulate well through the cores. At highway speeds I think the heat was hotter before the flush but after the flush its about the same once the temp gauge comes up regardless of speed.

I had a shop flush mine since its been single digits F around here and I have no inside space to to work. Another member recently had the same issue (maybe his never got hot) and he back flushed his core himself with a garden hose.
__________________
96 Burb K25 3.42's 320K miles so far, told its all original, front bumper grey pmd otherwise stock, close race between engine wearing out or body completely rust out.
95 Burb K25 3.73's 250K miles, looks to have been rebuilt at least once, stock, bad rust, 8' western plow.
81 Buick Riviera with the infamous Olds 5.7 diesel still going strong.
13 VW Jetta Sport Wagon TDI of course, does low 40's around town and can see 50's on the highway.
Online   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Diesel Place : Chevrolet and GMC Diesel Truck Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

PLEASE READ! You must check your email inbox for the confirmation link to complete registration. Please check your spam box if you do not see the email in your inbox.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Poor Cab Heat byacey 6.5L Diesel Engine 40 02-21-2011 11:08 PM
Poor front Heat bigbassg Interior 2 01-30-2009 09:36 AM
poor heat on drivers side firelakekid Duramax First Generation: 2001-2004 (LB7) 11 01-25-2007 01:51 AM
Poor Start + White smoke = WTF damowman 6.5L Diesel Engine 10 05-30-2006 08:07 PM
Poor floor heat? DuckDog Duramax Second Generation: 2004.5-2005 (LLY) 2 01-09-2004 12:06 PM


All times are GMT -4. The time now is 02:35 PM.


Shoutbox provided by vBShout v6.2.1 (Lite) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd. Runs best on HiVelocity Hosting.
© AutoGuide

SEO by vBSEO 3.6.0