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No heat on 1996 Caprice Classic 350 gen2
Sent to Car Experts August 28 02:53 PM

The Heater & defroster on my 1996 Caprice blows cool air. How do I diagnose? In the older cars it was usually a thermostat or heater core, but on the 1996 Caprice Classic with Gen 2 350 , I'm not sure if its that simple.

Customer (name blocked for privacy)
Status:  Closed   Value: $5
Info Request
August 28 4:29 PM (1 hour and 36 minutes later)
         
Go under the hood and feel the temp of the 2 heater hoses where the go through the firewall and see if they are both hot.
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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2714 Car Accepts
ASE Mastertech with Adv level Engine performance cert.
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August 31 12:24 AM (2 days and 7 hours later)
         
First off, thank you for taking the time send me an initial reply Hammer time. I was reluctant to enter in a charge card number, but I went ahead and did it. Hope this website is secure.

Here's what I found...

I drove the car out on the highway today and oddly enough, I did get some heat, but only when I put the setting to VENT and temp dial to hot while driving 60 mph. It would initially come out hot, then gradually fade back down to luke warm.

If I turned the dial to OFF for a few minutes and then back on to VENT setting, with the Temp dial set to hottest , the same thing would happen. (Starts out hot, then gradually fades to luke warm...) I tried this again, but under hard acceleration. No difference. The temp gauge does
not appear to indicate any overheating.
(but its a stock Caprice dash cluster gauge)

When I set the dial to the HEAT setting, the airflow switched to the vents located under the center of the dashboard just above and to left and right of the tranmission hump.

The air that came out was actually cooler when I used the HEAT setting than when using the VENT setting. The air would get luke warm (if even that) and then get cooler again.

I also tried moving the temp dial from hot to cold, and back to hot.
Actually caused the air to get even cooler even after returning the dial to hot setting.

I also tried the DEFROST setting but the air that came out of the defroster vent was also cooler. I tried turning off for few minutes (while still driving 60 mph) and back on again but setting it to HEAT. The air was still cooler out the bottom heat vents than it was when I set the dial to the VENT setting. (front vents facing passengers)

When I got home with the car, I popped the hood and felt the heater hoses. One upper hose was hot, the lower one was very hot. The top hose goes
to tube just under the t-stat housing near top of the water pump. The lower one disappears under the water pump.

I crawled under the car with a flash light and still couldn't see exactly where the lower one feeds in at.

I can tell you that the air flow DOES get re-directed from the front vents to the vents underneath when I turn the dial from VENT to HEAT. That would seem to confirm that at
least some of the vacuum systems are working correctly.

Coolant Maint history.
The car has approx 94000 miles on it.
I have had the water pump replaced on 11/19/2004 by GM Goodwrench at 83644 miles. Also had oil, filter, intake manifold gaskets, pvc valve, serpentine belt replaced at that time and complete engine coolant flush. (dex cool)

Prior to that at 55121 mile, had heater core replaced and engine flushed on 4/3/2002.
(GM goodwrench)
Car was under First Extended warranty until 92443
miles.

Prior to that, the Radiator was Flushed and filled with dexcool at 46578 miles on 10/22/2001

I bought the Car on 7/21/2001 with 43443 miles on it. (I doubt the prior owner did anything to the car other than oil and filter.)

That's probably why the heater core clogged up. Six years on same coolant. (probably gummed up the whole cooling system. That's why I had it flushed at 46K but it still bit me anyway...
Is it wise to keep useing dex cool?
The owners manual says 5 years or 100,000 miles for the coolant. (yeah right...)

There is a mechanical Fan and an aux elec fan to the left side of radiator. The car came equipped with towing package.

I have a complete maint log avail if you want it.
(I did not skimp on maint)

The thought of blindly tearing out the under side of the dash does not seem very appealing. If I knew what I was looking for I'd be more apt to give it a go... These reverse flow cooling systems
are confusing to me. (not sure I fully understand how they work) These 1996 cars seem to have a lot of electronic control gizmo's on them.

Look forward to your reply.
Thx..

Gary M. Hagan

P.S. I really like this car alot despite its complexity. I recently had an impala grille put on it. (makes it a little sportier looking)
I'm 43 years old and have two kids and wife so needless to say my soup up the car budget is
is non-existant. I'd love to put some mods on
this car...there's tons on bolt ons avail...

Customer (name blocked for privacy)
Answer
August 31 12:54 AM (30 minutes and 6 seconds later)
         
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Kevin Shaw -- Auto Mechanic -- 100% Positive Feedback on 2 Car Accepts
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August 31 6:17 AM (5 hours and 22 minutes and 54 seconds later)
         
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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2714 Car Accepts
ASE Mastertech with Adv level Engine performance cert.
Reply
September 1 8:18 AM (1 day and 2 hours later)
         
I only have 10,000 miles on the coolant since the waterpump was replaced. I can't flush the cooling system myself. (I don't have the special equipment - valves etc)

I can mockup some garden hoses and spare heater hoses to backflush the heater core. Should I attempt to put any kind of heater core cleaning solvents into the core prior to flushing?
Customer (name blocked for privacy)
Answer
September 1 8:47 AM (29 minutes and 39 seconds later)
         
ACCEPTEDCheck Mark
Since you can't flush the rest of the system, leave the chemicals out. Remove both heater hoses and use a garden hose to force water in both directions until it flows smoothly. I suspect there is more still in the rest of the system though so it may clog again in the future.
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Hammer Time -- L1 Master Technician -- 98% Positive Feedback on 2714 Car Accepts
ASE Mastertech with Adv level Engine performance cert.
Reply
October 2 5:11 PM (31 days and 8 hours later)
         
Finally got to flush the heater core today. Some crud did come out... Flushed in both directions till water ran clear.

Heater is working now. Looks like this did the trick. Thanks for the info Hammer Time.


Customer (name blocked for privacy)
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