On Sunday, July 9, 2017 at 9:17:03 AM UTC-4, Ed Pawlowski wrote:
On 7/9/2017 4:24 AM, Vic Smith wrote:
On Sat, 8 Jul 2017 20:03:26 -0700 (PDT), trader_4 wrote:

On Saturday, July 8, 2017 at 10:40:53 PM UTC-4, Vic Smith wrote:
On Sat, 8 Jul 2017 21:46:08 -0400, Ed Pawlowski wrote:

On 7/8/2017 8:58 PM, Vic Smith wrote:


No it's not misinformation. Anybody who's ever replaced a heater core on GM vehicles that
I know of, know that the core has an inlet and outlet and no valves restricting flow.
It's the job of the mixer door to adjust heat in the cabin. There are some vehicles that
have heater water valves, but I haven't worked on them.
And their is no "extra" heat.
Engine designers can't eliminate waste heat until they design one that's 100% efficient.


It has been probably 40 years since I played with heater cores, but I do
know there was a valve in the line to stop the flow. Maybe thing have
changed?

https://www.yourmechanic.com/article...hard-zeppetini

Google heater core valve and then click on images.

This is GM specific
https://www.google.com/search?q=heat...w=1366&bih=638

Like I said, "There are some vehicles that have heater water valves, but I haven't worked
on them." I've owned only Chevy cars and one van, and a Grand Am since about 1975.
NONE of them had a heater valve. Nor did my 1966 F100 Ford PU, or 1973 Dart.
Pretty sure you'll find that cars without heater water valves are as common as Chevys.

Maybe you just need to look harder?

http://www.ebay.com/itm/HVAC-Heater-Control-Valve-Heater-Valve-Front-4-Seasons-74603-/272744018440?fits=Make%3APontiac|Model%3AGrand+Am& epid=75725794&hash=item3f80cf7208:g:BhoAAOSwq7JUAT Wl&vxp=mtr

If you give us the year for the vehicles in question
we can look at accurate part info. But just googling
for Pontiac Grand Am, looking on Ebay, etc obviously
at least some of them used heater valves.

I'll repeat, "There are some vehicles that have heater water valves, but I haven't worked
on them." Here's my Pontiac. 1995 Pontiac GT. 3.3 liter engine. Good luck finding the
non-existant heater control valve. My 2003 Chevy Impala with the 3.4 likewise.
Won't bother naming all the vehicles I've had with no heater control valve. All of them.
A valve on a heater hose is too obvious to miss for anybody who works on their engines, and
hose maintenance comes with the territory.
I see the '66 F100 came equipped with one, but it was gone before I personally removed
the 352 ci engine twice, replacing all hoses once. I never missed it.


Sorry Vic, but I found it in less than a minute. Please, stop it. Cars
have heater valves. Exception being air cooled engines. My Corvair and
Karmen Ghias did not have them.

https://www.google.com/search?q=1995...X9v7JjSEMp7iM:

I was trying to look up the specific part at part
stores, but didn't get past that there is no 1995 Pontiac GT. Was that a Firebird Transam GT or
something? I think you have to be careful with just general google searches because a lot of time
they come back with hits for aftermarket things
you could add, ie generic extra widgets, that are
not part of the car.

From some other googling, I found at least one
place that said that some cars do have the system
these guys are talking about, where they just
modulate the air flow and don't control the coolant
flow. That kind of design doesn't make any sense
to me for the reasons cited. But I still doubt
Clare's position that the vast majority of cars
are built that way now. Also, IDK what exactly
"now" means. If this big shift has occurerd, I
think it has to be only in much more recent years,
not back in 1995. The designs I've seen, the air
flowed through both the heating and cooling cores
and the coolant through both cores mas modulated
by valves according to need for heat or cooling.