Improving A/C Performance

[brian bray]

I live in Tucson, AZ where the summer temps often exceed 100 degrees F. I have an 1991 300 SL which has an excellent A/C system (you could freeze meat in my car!) including 2 aux fans set to turn on automatically at slow or fast speed depending on the coolant temperature. This system works as designed.

However, I made two very minor INEXPENSIVE upgrades that are relatively easy:

1) Replace the radiator cap ($6 at Pep Boys, etc.). On my car, it's a 20 lb cap which means that as the pressure builds up to anything below 20#, the coolant doesn't boil or escape out the overflow causing the car to overheat. (If any car repeatedly overheats, the head will warp requiring a very expensive repair). So a new $6 cap may keep the car from overheating.

2) My car (like most older cars) has an unused cigarette lighter and ashtray in the center console. If you remove the ash tray, that space will hold a large foam cup of water, etc. saving you the cost of buying a dumb looking add-on cup holder. If you unplug the the wires from the back of the lighter element and remove the element and go to ACE Hardware and buy a push switch ($5) that fits into the element. Drill out the element and install the push switch where the lighter previously went. Nothing is visible; No holes or weird switches in the dash, etc. I included 2 inline fuses wiring everything so that the fans still will come on automatically as designed.

BUT, push the switch bypassing the automatic system turning the aux fans on high at any time.
Push the switch again and the system reverts back to the automatic system. Everything shuts off when the ignition is off.

The advantage is that I can turn the fans on earlier than the auto system or I can keep them on longer helping the cooling system operate at max even if in slow traffic on a blistering hot day.

 

[range rover]

I live in Tucson, AZ where the summer temps often exceed 100 degrees F. I have an 1991 300 SL which has an excellent A/C system (you could freeze meat in my car!) including 2 aux fans set to turn on automatically at slow or fast speed depending on the coolant temperature. This system works as designed.

However, I made two very minor INEXPENSIVE upgrades that are relatively easy:

1) Replace the radiator cap ($6 at Pep Boys, etc.). On my car, it's a 20 lb cap which means that as the pressure builds up to anything below 20#, the coolant doesn't boil or escape out the overflow causing the car to overheat. (If any car repeatedly overheats, the head will warp requiring a very expensive repair). So a new $6 cap may keep the car from overheating.

2) My car (like most older cars) has an unused cigarette lighter and ashtray in the center console. If you remove the ash tray, that space will hold a large foam cup of water, etc. saving you the cost of buying a dumb looking add-on cup holder. If you unplug the the wires from the back of the lighter element and remove the element and go to ACE Hardware and buy a push switch ($5) that fits into the element. Drill out the element and install the push switch where the lighter previously went. Nothing is visible; No holes or weird switches in the dash, etc. I included 2 inline fuses wiring everything so that the fans still will come on automatically as designed.

BUT, push the switch bypassing the automatic system turning the aux fans on high at any time.
Push the switch again and the system reverts back to the automatic system. Everything shuts off when the ignition is off.

The advantage is that I can turn the fans on earlier than the auto system or I can keep them on longer helping the cooling system operate at max even if in slow traffic on a blistering hot day.

Heaven forbid we get 100f the climate change fanatics would have a field day!

 

[Blobcat]

Heaven forbid we get 100f the climate change fanatics would have a field day!

Agreed, I see in the news the extinction rebellion are wanting to get carbon emissions to net zero by 2025 - to do that all gas boilers would have to be replaced with electricity which would mean an additional 130,000 wind turbines according to the researchers at Zero Carbon Britain.

There is an elephant in the room of monumental proportions which all these protesters ignore - wind turbines are in no way zero carbon, the carbon released in the production, shipping, installation and maintenance is huge. However as most of it isn't in Britain then it's not counted...

We only have 1 planet so cutting carbon here but releasing it elsewhere isn't green in the slightest.

 

[LostKiwi]

Replace the radiator cap ($6 at Pep Boys, etc.). On my car, it's a 20 lb cap which means that as the pressure builds up to anything below 20#, the coolant doesn't boil or escape out the overflow causing the car to overheat. (If any car repeatedly overheats, the head will warp requiring a very expensive repair). So a new $6 cap may keep the car from overheating.

That's not preventing overheating, just delaying the point at which coolant boils.
The overheating condition still exists up until that point.
Far better to ensure the the temperature never gets that high in the first place. My 129 spends most of its life in western France and we also regularly get 100F temperatures in summer. If my engine temperature exceeds 100C (212F) I'll stop driving till it cools (fortunately only happened once).

 

[umblecumbuz]

1) Replace the radiator cap ($6 at Pep Boys, etc.). On my car, it's a 20 lb cap which means that as the pressure builds up to anything below 20#, the coolant doesn't boil or escape out the overflow causing the car to overheat. (If any car repeatedly overheats, the head will warp requiring a very expensive repair). So a new $6 cap may keep the car from overheating.

What the man says is fundamentally correct. If you lose coolant volume through a poor radiator cap, you also lose heat sink capacity. The reduced volume will then have less resistance to varying engine loads, and the possibility of overheating will be increased.

An ingenious low cost approach to a potentially terminal hiccup!

 

[LostKiwi]

What the man says is fundamentally correct. If you lose coolant volume through a poor radiator cap, you also lose heat sink capacity. The reduced volume will then have less resistance to varying engine loads, and the possibility of overheating will be increased.

An ingenious low cost approach to a potentially terminal hiccup!

Yes if the old cap is duff but if the old cap is good then it's better not to get to the boiling temperature in the first place.
Treat the cause, not the symptom.

 

[JohnArnoldBrown]

Agreed, I see in the news the extinction rebellion are wanting to get carbon emissions to net zero by 2025 - to do that all gas boilers would have to be replaced with electricity which would mean an additional 130,000 wind turbines according to the researchers at Zero Carbon Britain.

There is an elephant in the room of monumental proportions which all these protesters ignore - wind turbines are in no way zero carbon, the carbon released in the production, shipping, installation and maintenance is huge. However as most of it isn't in Britain then it's not counted...

We only have 1 planet so cutting carbon here but releasing it elsewhere isn't green in the slightest.

The latest report I read said that a turbine built to last 20 years would pass the carbon neutral point in less than a year.
Are you sure your pachyderm isn't just a couple of oil company lobbyists in an elephant costume?

 

[Blobcat]

The latest report I read said that a turbine built to last 20 years would pass the carbon neutral point in less than a year.
Are you sure your pachyderm isn't just a couple of oil company lobbyists in an elephant costume?

No

 

[LostKiwi]

We're venturing off topic but what surprises me is that we are investing so much in a source of power which is neither constant nor guaranteed.
This goes equally for solar.
We have a ready source of power that's guaranteed every six hours yet little seems to be done with it.
Tidal power whilst not constant is guaranteed.

 

[range rover]

We're venturing off topic but what surprises me is that we are investing so much in a source of power which is neither constant nor guaranteed.
This goes equally for solar.
We have a ready source of power that's guaranteed every six hours yet little seems to be done with it.
Tidal power whilst not constant is guaranteed.

Don't forget hydro!

 

[LostKiwi]

Don't forget hydro!

Very few places Inthe UK suitable for it.

 

[andrew056]

Perhaps all these wind turbines are causing climate change by changing weather patterns.

 

[John Laidlaw]

Horse, carts, windmills and water mills are the future

 

[range rover]

Very few places Inthe UK suitable for it.

On my small river in the 1800's there were 13 sites where hydro power was used for various uses, when I applied for an abstraction licence I was at first refused on the basis that there are already 2 sites! I couldn't believe what I was hearing, they eventually relented as my site was close to another and would be classified as 1. The point I am making there are lots of small former mill sites lying unused which could and should be resurrected, there is nothing quite so sweet as a water turbine spinning around the only noise coming from the cooling fans of the generator, and the money helps too!

 

[LostKiwi]

On my small river in the 1800's there were 13 sites where hydro power was used for various uses, when I applied for an abstraction licence I was at first refused on the basis that there are already 2 sites! I couldn't believe what I was hearing, they eventually relented as my site was close to another and would be classified as 1. The point I am making there are lots of small former mill sites lying unused which could and should be resurrected, there is nothing quite so sweet as a water turbine spinning around the only noise coming from the cooling fans of the generator, and the money helps too!

Small personal hydro systems maybe, but not the multi MW ones that commerce requires.

 

[Tony Dyson]

Pico <5 kW and Micro Hydro Generators <100 kW are rare in the UK but as time goes by they are becoming more affordable and popular where the right environment exists. LK is right we just don’t have the terrain providing the head and volume of water needed for anything of any significant size in the UK.
The biggest Hydro installation is in Dinorwig, Snowdonia, where a 1.8 GW Power Station was built 750m into a mountain to generate peak power from a reservoir situated 70m above, collecting the spent water in a pond below, then using off peak electricity from the National Grid to pump all the water back to the top reservoir overnight. The Power Station is designed as a Peak Power contributor as it can be brought online from resting to max output in less than a minute to cater for all the kettles at meal times throughout the day.

 

[Blobcat]

Pico <5 kW and Micro Hydro Generators <100 kW are rare in the UK but as time goes by they are becoming more affordable and popular where the right environment exists. LK is right we just don’t have the terrain providing the head and volume of water needed for anything of any significant size in the UK.
The biggest Hydro installation is in Dinorwig, Snowdonia, where a 1.8 GW Power Station was built 750m into a mountain to generate peak power from a reservoir situated 70m above, collecting the spent water in a pond below, then using off peak electricity from the National Grid to pump all the water back to the top reservoir overnight. The Power Station is designed as a Peak Power contributor as it can be brought online from resting to max output in less than a minute to cater for all the kettles at meal times throughout the day.

It’s a great place to visit as well, turbine hall very impressive.

It uses more electrickery than it generates as it’s there to fill in for peak demand and use the gas and coal spare night electrickery to pump the water back up the hill.

Of course if the gas and coal are switched off there isn’t the spare night electrickery to pump the water back up...

 

[Tony Dyson]

It’s a great place to visit as well, turbine hall very impressive...

The Turbine Hall was known as the Symphony Hall during the Construction Phase due to the acoustic qualities when empty. It was the biggest project of it's kind in Europe at the time it was commissioned, I don't know if that accolade still exists?

 

[Flyinspanner]

Back to the thread.......

@brian bray have you investigated using a waterless coolant fluid, could maybe help in your situation.

http://www.evanscoolants.co.uk/

I’m sure there are similar available in the USA.

 

[McDonald]

Hello Brian, I'd be interested in seeing a picture of your car and of the modification you made around the cigarette lighter. Keeping your engine cool in extreme temperatures is a worthwhile preoccupation, especially as you live in a region known for it's desert.