Poor Heat, Not Sure Where to Start - Page 2 - 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 01-02-2013, 11:51 AM   #11 (permalink)
JMJNet
Diesel Laureate
 
JMJNet's Avatar
 
Join Date: Feb 2006
Location: Richardson, TX
Posts: 12,011
iTrader Score: 0 reviews

The Suburban Club Member

Also, another possiblity is the Blower Resistor.

It happens when you dial the control from low med hi, it does not change the fan speed.

In mine, it is behind the glovebox right above the duct.
A little bit tricky to take out.
__________________
1995 GMC Suburban:
PMD in Bumper
4" Warpspeed Exhaust
KD LP/OPS Harness
Bosch Duraterm GP
Heath Turbo-Master
Chevron's XLP Diesel Additive

Last edited by JMJNet; 01-02-2013 at 11:57 AM.
Offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 01-02-2013, 06:16 PM   #12 (permalink)
GbByChubsy
Diesel Specialist
 
GbByChubsy's Avatar
 
Join Date: Sep 2010
Location: Dublin, Ohio
Posts: 508
iTrader Score: 0 reviews

The Suburban Club Member

I just had about two coolant flushes in the past three weeks due to head replacement and subsequent temp sensor replacement. do you guys mean the actual heater core behind the dash is clogged?

As for the resistor, not sure. Fan speed does change but I will look at the resistor.

This is quite annoying to say the least. I do not want to replace the heater cores or the blower because they still work and I do not think that those units as a whole or at fault, rather issues within them that can be fixed....

So I suppose the answer to the heater core/coolant flush question I posed just now and any other things with the fellows who had the same issue a few weeks back?
__________________
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, 09:00 PM   #13 (permalink)
tookielee
Diesel Specialist
 
tookielee's Avatar
 
Join Date: Dec 2007
Location: Port Vincent, Louisiana (near Baton Rouge)
Posts: 758
iTrader Score: 0 reviews

If your airflow is poor, you won't get hot air... it has to flow THRU
the fins to warm up. I changed my evap core because of a leak,,
and changed the heater core while it was out. After the change, airflow
on low was better than it was on high before the change. GM should
have put cabin filters in these trucks.
Find an AC repair shop, pull the blower and pay them a few bucks
to spray a solvent in there to clean out the fins, then you rinse it off.
__________________
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 01-02-2013, 11:56 PM   #14 (permalink)
handcannon
Diesel Specialist
 
Join Date: Jul 2009
Location: Albany, OR
Posts: 674
iTrader Score: 0 reviews

Quote:
Originally Posted by GbByChubsy View Post
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.
On a van I used to drive for work I soon found that any time the heater did like you are saying I knew to check the coolant level. Low coolant meant no flow through the heater core at an idle. At higher speeds the coolant would flow through the heater core.

For you it may or may not be coolant level, but something is reducing coolant flow through the heater core at an idle. Once the motor RPMs go up the coolant starts to flow better and then can go through the heater core. How new, or good of shape are the heater hoses?

I hope this helps you trace down the no heat problem.

Don
__________________
1983 Chev 1/2T pickup, 6.2 and 700R4 to become a heart transplant for my 1971 Toyota FJ 40

1994 Chev 3/4T heavy duty 6.5 TD 4X4 extended cab w/4.10 gears. turbomaster, intake snorkle removed, PMD relocated, OPS relay mod, all on headlights mod, Diamond Eye 3" down pipe and 4" exhaust, Glowshift gauges, homegrown version of feed the beast, TCC lockup mod.
Most recent mods are 2000 year model HO water pump, Heath low temp fan clutch, DMax 9 blade fan, 4X4 Posi-Lok.
Offline   Reply With Quote Quick reply to this message
Old 01-03-2013, 10:18 AM   #15 (permalink)
bigblazer
Diesel Technician
 
bigblazer's Avatar
 
Join Date: Jan 2012
Location: mcallen tx
Posts: 411
iTrader Score: 0 reviews

Air bubble an cause what your describing. If on low fan setting theres decent heat but gets cooler as soon as you turn the fan to high, theres a core restriction. If it gets warmer when you rev the motor, sometimes you can hear water and air bubbles gurgling under the dash, its an air pocket or low coolant level.if your blower speed changes dont bother looking into the resister.
__________________
94 Chevy blazer. 929 block, hd 4l80e, pmd relocated in bumper, #9 resister, ssd "80" hp chip, gm8 with DIY boost controller now 18psi, 3 down tube 4" straight pipe 5" tip, k&n cone, optic bump, kennedy injectors, boost/egt/trans/oil pres/water temp gauges, 3 core aluminum radiator w/dual fans, 98 "h.o" w/p with restricters installed, cowl hood. 4.10s in 14b semi floater, 35 firestone m/ts 8" rough country lift 3" body lift. Dos cientos quatro whp As of 2/21/13 thats all she's gonna put out!
Offline   Reply With Quote Quick reply to this message
Old 01-03-2013, 11:11 AM   #16 (permalink)
smokydiesel
Diesel Head
 
Join Date: May 2012
Posts: 25
iTrader Score: 0 reviews

Quote:
Originally Posted by GbByChubsy View Post
I just had about two coolant flushes in the past three weeks due to head replacement and subsequent temp sensor replacement. do you guys mean the actual heater core behind the dash is clogged?

As for the resistor, not sure. Fan speed does change but I will look at the resistor.

This is quite annoying to say the least. I do not want to replace the heater cores or the blower because they still work and I do not think that those units as a whole or at fault, rather issues within them that can be fixed....

So I suppose the answer to the heater core/coolant flush question I posed just now and any other things with the fellows who had the same issue a few weeks back?
My ( im that fellow) heater core in the dash had a ton of rusty sediment in it i back flushed it with a garden hose by taking the hoses off at the intake manifold and upper radiator locations
Offline   Reply With Quote Quick reply to this message
Old 01-03-2013, 12:36 PM   #17 (permalink)
Graplr
Diesel Specialist
 
Graplr's Avatar
 
Join Date: Aug 2009
Location: Stillwater, Minnesota
Posts: 762
iTrader Score: 0 reviews

Minnesota/Western Wisconsin DP Club Member

Gb,
First make sure your coolant level is topped off. Since you just changed it air could have worked itself out and you are low. As mentioned, an air pocket (which is common after a coolant change) could be the cause.

Also, did you do an actual flush? Or did you just refill the engine with coolant? If you didn't flush the heater core out, that is what I would do next after verifying Tue coolant level.

Your description in your first post made it seem like an air flow issue but your following descriptions make it seem like a coolant flow 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
Offline   Reply With Quote Quick reply to this message
Old 01-03-2013, 02:43 PM   #18 (permalink)
GbByChubsy
Diesel Specialist
 
GbByChubsy's Avatar
 
Join Date: Sep 2010
Location: Dublin, Ohio
Posts: 508
iTrader Score: 0 reviews

The Suburban Club Member

Well lets hammer these questions out:
1. The heat does not change when the fan intensity. If on high, it still blows as warm as it does on low so no difference there.
2. The air flow seems ok, not great but ok. Not nearly ass good as our 06 1500 gasser Burb but ok.
3.. At times the blower motor won't activate when you turn the air on; however, by simply hitting the black box under the dash where it is located activates it fine.
4. Actual coolant flush. To replace the temp sensor I lost basically all coolant. Before that most was drained out when we did the head replacement. And again a full flush was done by the shop when they sodered the temp sensor to the wiring harness.
5. If I squeeze the upper intake hose to the radiator, I can hear the coolant slush around, so not sure if that is 1005 normal or if there really is more air in the system after the flush than there should be.

So, should I first try to top of the system and drain out the air through the valve on while the truck is running or....????
__________________
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 01-03-2013, 02:44 PM   #19 (permalink)
GbByChubsy
Diesel Specialist
 
GbByChubsy's Avatar
 
Join Date: Sep 2010
Location: Dublin, Ohio
Posts: 508
iTrader Score: 0 reviews

The Suburban Club Member

Getting down to single digits here which is when we really consider it to start getting cold so this is really becoming a huge problem.
__________________
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 01-03-2013, 03:07 PM   #20 (permalink)
FloridaHorseman
Diesel Master
 
FloridaHorseman's Avatar
 
Join Date: May 2011
Location: Lakeland, FL
Posts: 3,202
iTrader Score: 0 reviews

Try disconnecting the firewall hoses to the heater and seriously back flush the core. And, yes. Bleed the coolant system at the valve above the thermostat with the engine at operating temp with heater controls on full hot and blower set at max..

The fact the blower motor has to be sometimes encouraged to start with a sharp rap on the heater box is not a good sign either. It may be on its way out and not spinning fast enough to circulate significant flow. And there's a cabin air filter somewhere in that mix that may also be completely clogged up. I don't know where it would be on a Suburban. Air trapped in the heater core renders the symptoms you have. If a thorough back flush and air bleed of the heater core doesn't improve things I'd say core and blower fan replacement would be my next course of action. ~FH
__________________

1994 Chevy K1500 Z71, 6.5L TD 145,000 miles, bumper mount PMD, LP relay mod, filter sock delete -SOLD-
1998 Chevy K3500, 454 horse hauler , 175,000 miles, tuned flow-through exhaust, pillar gauges (vac, trans temp, volts), electric cooling fans, external trans cooler & fan, manual TCC lockup mod, limo tint, front & rear brush guards, B&W G/N flip hitch, spray-in bed liner, chrome wheel inserts


Engine "No Start" Checklist
Diagnostic Checklist
OBD1 Trouble Codes
OBD2 Trouble Codes

Last edited by FloridaHorseman; 01-03-2013 at 03:08 PM.
Online   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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 05:43 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