440 heating up only when AC switched on

[josephqatarcarguy]

Hey guys , my 1973 challenger 440 heats up when AC is turned on , only when AC is on , goes to 220 , does not puke over , starts right back up if I switch her off , mechanical gauge on the water pump housing , 4 core 26 "rad with dual spal fans wat should I look at ? High volume thermostat 180, hw water pump , lower hose has spring , timing set at 15 initial, 33 total , with AC off cruises at 190 , I live in qatar and in summers the temps are 112 degrees

Thanks

 

[BLK 68 R/T]

Seal all air gaps around the radiator. I’m gonna go ahead and guess it’s airflow related.

 

[5.7 hemi]

A mechanical fan will always pull more CFM than the electric fans. If you’ve got the room, put a mechanical fan and shroud on it and if need be use an electric pusher fan on the other side that way you’ll still get cold ac during low speed slow traffic times.

 

[Rishi]

In my experience, a 26-inch radiator is capable, by its width, of keeping even the hottest-running engines cool, unless there are issues with air flow, fan shroud, thermostat, etc. Some 26-ers have fewer cores than others, but if its only over heats when firing up the A/C, then your cooling system is not 100%, and gets overrrun when the A/C is on.

Not a beg deal, many of us have seen it. But it IS A SIGN your cooling system could be better.

 

[josephqatarcarguy]

Seal all air gaps around the radiator. I’m gonna go ahead and guess it’s airflow related.

Will check that out

 

[josephqatarcarguy]

A mechanical fan will always pull more CFM than the electric fans. If you’ve got the room, put a mechanical fan and shroud on it and if need be use an electric pusher fan on the other side that way you’ll still get cold ac during low speed slow traffic times.

These electric fabs really moves a ton of air , I use it on all the cars I build here and temp only climbs up while on the move so fan is not the culprit

 

[Geoff 2]

Smaller water pump pulley to pump more water. Losing the elec fans would also be a good idea.......

www.stewartcomponents.com

 

[1STMP]

Smaller water pump pulley to pump more water. Losing the elec fans would also be a good idea.......

www.stewartcomponents.com

I run a single 3800 cfm fan
on an aluminum 2 core rad.
After the 440 was broke in,
I rarely see temps past 190
in stop and go at ambient
air temps around 100.

There's 1000's out there that
run similar set-ups with no
issues.
In the OP'S case, I would
check for restricted flow,
weak antifreeze, or a bad rad
cap.
Adding a bottle of Water
Wetter may help if the rad
and cap checks out.
One more thing to check
would be the charge in the
A/C system.

 

[HawkRod]

Remember that the condenser (the "radiator" of the A/C system) sits in front of the radiator. When your A/C is blowing cold, guess where all that heat goes? Yep, the condenser dissipates it, and then that warm air that just pulled heat out of the condenser blows through your radiator to cool it.

The bottom line is you are always going to have an extra heat load on your system when the A/C is running, so having it run a few degrees hotter is normal. Having said that, I agree to make sure your radiator is in good shape and not partially plugged. A good flush and check isn't a bad idea.

 

[1967coronet]

If the temp is coming up at road speed I agree on the air flow or lack of.
Check all rubber seal strips , cowl to hood, hood to radiator support, bottom splash panel between the grille / bumper and radiator support.
If it's a after market radiator does it fit flush to the support ?
If you have one of the flat shrouds with a fan mount hole those things block a lot of air flow once moving.

 

[josephqatarcarguy]

If the temp is coming up at road speed I agree on the air flow or lack of.
Check all rubber seal strips , cowl to hood, hood to radiator support, bottom splash panel between the grille / bumper and radiator support.
If it's a after market radiator does it fit flush to the support ?
If you have one of the flat shrouds with a fan mount hole those things block a lot of air flow once moving.

Fan a derale unit I use on all the classic cars I build here in Qatar

Here a pic of the bay

 

[1967coronet]

Fan a derale unit I use on all the classic cars I build here in Qatar

Here a pic of the bay

View attachment 1671335

If yo have a shroud simular to this one your really blocking alot of flow when moving.

 

[josephqatarcarguy]

hey guys , the car still heats up but only while highway driving with ac on!!! comes to a stop and the temps go right down ? could it be the radiator? temps sneaks upto 210 ...215 ... come to a stop and comes right back down

 

[Geoff 2]

It could be rad.....& many other things.

 

[gtxdana]

hey guys , the car still heats up but only while highway driving with ac on!!! comes to a stop and the temps go right down ? could it be the radiator? temps sneaks upto 210 ...215 ... come to a stop and comes right back down

Use an infrared thermometer to check for colder areas on the radiator indicating a partially plugged radiator.

 

[oldbee]

Spring in lower radiator hose? Maybe partially collapsing.

 

[Geetex]

Spring in lower radiator hose? Maybe partially collapsing.

That's what the spring is supposed to prevent.

 

[josephqatarcarguy]

Spring in lower radiator hose? Maybe partially collapsing.

yes springs there in the lower hose

 

[oldkimmer]

I always run a 195 T stat. ALWAYS! Kim