No heat - 94 Brougham - Help!

[David #19063]

Hello,

My 94 Brougham does not put out any heat.  Or I should say barely cool to luke warm.  Which when it is 20 F outside really bites.

I do not have a shop manual for the car yet.  A friend and I are going to look at it tomorrow.  He works on his classic cars.

What are all the things that can cause this?

Simple and difficult.

I think the car had heat when I first got it.  I just got it out of the shop as it had new plugs, wires, steering damper, and trans cooler and oil cooler lines replaced.

Could they have bumped or accidentally disconnected something?

Or what else could it be?

Thanks in advance!

David

[Kevin M. Parkinson 20216]

The problem could be a clogged heater core.  I replaced the heater core in my 1990 Deville 3 times.   The symptom was the same as you have described and all the heat I needed after replacement.

[Bob Chesnutt #21760]

The 90s Cadillacs are known to have the heater core clog on the outside in the fins.  This is indicated by lack of air flow as well as not getting hot.

If that is your indication, I have a friend who somehow got to it without taking it out of the car or going to all the work of removing part of the dash to clean it.  

If that is your problem, let me know and I will give you his e-mail and telephone.  My e-mail is bobandhelen@aol.com

[David #19063]

Hello Bob,

I seem to have good air flow, just not warm.

I hope it is something simple.

David

[Mike #19861]

 Since there is no temperature gauge, you cant be really sure if the engine is making it to operating temperature. But there are other things you can do.

 After the engine has been running awhile, feel the temperature of the hoses. If they are all hot, then the engine is coming up to temperature. If they are warm and you can comfortably hold your hands on the rad hoses, then the thermostat needs to be replaced.

 If they are all hot, feel the temperature of the heater hoses, if they are both hot and the same temperature, then the heater core is OK. If one is hot, and the other cold, then the heater core needs to be replaced.

 Follow the heater hoses and check to see if there is a heater flow control valve. If there is, they are most often vacuum controlled. make sure the hose os connected if it is, or if it is electrically controlled, make sure the connector is properly connected and clean and dry. I cant remember off hand if these cars use one or not.

 If, for any reason, the cooling system was messed with, ie drained and refilled, while you had it serviced, it may not have been bled properly. These engines employ reverse flow cooling and require a special bleeding procedure. If it was not done properly, then that could lead to your problem, and spells of overheating.

  Mike

[Tod - North TX CLC]

I just fixed this one last weekend.  As you said, after 30 minutes of driving, there would still be virtually no heat in the car.  All other systems appear to be working fine (fan is responding to climate control settings, etc).

The first step is to check for flow through the heater core.  Unlike most cars, the flow from the cooling system through the heater core is NOT managed through any vacuum valve, but is a constant flow.  By checking the incoming and outgoing temperature of the hoses (just by feeling the hose), I know that there was no or little flow through the core - return hose remained cool as incoming hose continued to get hot.

I simply removed the clamps from both hoses, took a garden hose and backflushed fresh water through the return hose.  I was amazed at the water that came out - just pure gross stuff, even though I have always changed the coolant on a yearly basis.

Once I put everything back together, I had heat within 5 minutes of starting the car.  

Try this - it only takes a couple of minutes, and will likely solve your problem.

[David #19063]

Tod,

Thanks, we may try that.  I did not know there was not a heater valve.

How is the heat controled then, buy a electric/vaccum door flap?

The shop did put in some cooling system sealant.  I wonder if that has something to do with it?

I guess I will find out.

Thanks!

David

[David #19063]

Tod,

One hose to the heater core gets hot, the other hose (the one that also attached to the overflow tank) does not, it gets barely warm.  

So I guess my heater core is mostly plugged.

Where did you disconnect the hoses?  Both at the waterpump or the one between the tank tee and the hearter core and the other at the waterpump?

I was wondering...I guess I need to back flush by putting in water from the house hose into the hose between the core and the tank?

Also, how to I then remove any trapped air?  I did see a bleeder screw at/near the waterpump.

David

[Mike #19861]

 Easy to do. I do it every year on the 86 Fleetwood.

 Remove both hoses from the heater core. Take the garden hose, just the hose with no fitting on the end, and place it over either one of the heater core pipes. Slowly turn on the hose. Be careful. If it is plugged, the sudden pressure from the house hose can burst the core before it is cleaned. Increase the pressure until you get good flow from the other pipe on the core. Then place the hose on the other pipe and repeat the procedure. Do this 3 or 4 times, and the core will be clean. Reinstall the hoses and you are good to go!

 A tip, use a couple of pairs of needle nose vice grips to crimp the heater hoses so that coolant loss is at a minimum when you remove the hoses from the core.

 It is possible that the sealant the shop used caused the core to plug. These cores are highly efficient, having many small tubes in an aluminum core. There are many more tubes than the old copper cores and they can plug much more easily if cooling system sealer is used.

  Mike

[David #19063]

Hello,

This afternoon (while there were snow furries and wind), I flushed the heater core.  I now have HEAT!  Although, I never did see anything come out but radiator fluid, but I did not watch extremely closely.

I disconnected the return heater hose at the waterpump and then put plastic over the waterpump tube and held it on with two rubberbands so I would not drain antifreeze out of the block.

The then disconnected the intake heater hose line on the firewall side of the "T" connector going up to the resevoir.  I left the resevoir cap on tight and this prevented the resevoir from draining out.

I then used my garden hose to gently flush the core out at low pressure.  Then after it flowed clear, higher pressure.  Then let it drain out and blew the core empty so I would not have tap water in the core.

I connected the lines, cracked open the antifreeze bleeder at the waterpump, and then added 3/4 gallons of distilled water to the resvoir.  Closed the bleeder as there only antifreeze coming out, no air.

Then started the engine and let it run 20 minutes, and open the bleeder again, no air, but I did have heat.

The level had not dropped.

Drove the car around the block with a few full throttle accerations.  Checked and the level was fine.

Thanks for everyone that gave me input!  

It saved me money doing ot myself!

David

[Bob Dziewit]

I experienced coolant loss due to a leaky heater core on a 95 Roadmaster (same system) and then had the problem Mike described in his last paragraph.  They have to be re-filled properly.  The problem is, I dont know what that procedure is because by that time, I had already given up and taken it to a radiator shop.  When I asked the technician, he just said to fill it very slowly (30-45 minutes with the engine running).

[Porter 21919]

This post will end up in the technical forum next time.

You need to let the air out of the system at a high point, usually near the heater core.

Porter

[Mike #19861]

 When did this happen?