Running Hot After A/C Installation Options

[m170seeker]

I have a '74 that I just installed the new A/C kit from Cooler Air. Now the engine runs hot (measured by the gauge which got right up to the red line). I don't think it is getting hot from the A/C system itself. When putting it in, I removed the Heater Flapper and dropped it once.

Is it possible that I simply broke the heater flapper and the engine heats up because it is not working?

[dakotaewing]

I have a '74 that I just installed the new A/C kit from Cooler Air. Now the engine runs hot (measured by the gauge which got right up to the red line). I don't think it is getting hot from the A/C system itself. When putting it in, I removed the Heater Flapper and dropped it once.

Is it possible that I simply broke the heater flapper and the engine heats up because it is not working?

I'm not stating this to be crase or rude, but most likely its getting hot because you live in Texas, it's 100 degrees, you have added an additional load to the engine by adding the A/C, and I would wager that you don't have an external oil cooler, much less a front mounted one...

I can't speak for the flapper issue, but it would appear that you have other issues outside of your control, such as where you live, and the temps that are contributing to the problem. As owners, we need to remember that these engines where not designed in our environment, but in a much cooler one - Add A/C which it was not designed for either and you have (IMG:style_emoticons/default/headbang.gif)

Do yourself a favor and add a big ass front mounted oil cooler, with fans, if you want A/C in an air cooled 914 -

I'm sure others have their opinions - this is just my $.0002

[SLITS]

An A/C compressor can draw up to about 5 HP (piston). Rotaries will consume less.

Cold air ain't for free.

You need to check the cooling system for one (passenger side flapper must be down to direct air to the cooler) and make sure the engine is in exact tune.

That's my $0.02

[Cupomeat]

Agreed about the additional drag and the ambiant temps, but what did you mean when you said you REMOVED the heater flapper?

If you removed the right side flapper (under the cooling tin), the engine will not properly direct air through the oil cooler and the engine will run hotter.

Please clarify and then we'll go from there.

[Brian_Boss]

Does it runner hotter now, with the A/C turned off, than it did before?

If not, it would indicate that the problem is not caused by having A/C per se, but by something that changed during the install.

Is there a large gap in the tin to accommodate the compressor?

[TheCabinetmaker]

I think he means the heater valve. It will have nothing to do with temp on your gauge as its measuring oil temp. Yes an extra draw from the ac will cause the oil temps to rise. Its 100 plus here too and my car runs considerably hotter oil temps as the air temp rises. i don't see the red, but it does get hotter. Slits is right about the rotary compressors. And what everyone said about the cooling air directional flap over the oil cooler. If you thermostat is inop make sure the flap is in the default position. An external oil cooler may be needed if the problem persist. A little extra oil (1/2 pint) will help a bit too. Dirt or debis around the cooler will also raise temps.

[TheCabinetmaker]

Do you have a link to the Cooler Air Kit?

[m170seeker]

Okay; I don't have a link to the Cooler Air kit but it is the dual condensor unit that AA sells. I don't think the AC system drag is heating it up. I can try the test (running it without the new air on) and report back on that one. Some of the sheet metal had to be cut out for the compressor but this kit is identical to the dealer installed kit so I don't think it is all that. the draft under the car changes due to a few cuts in the body and the ac hoses coming through the racket pinion steering cover. Also, not nearly as much space is left between the engine and the firewall with the condensor and the electric fan mounted there.

I'm hoping it is as simple as the heater flap being stuck or something. I removed it and reinstalled it (intending to put it back just like it was). I'm not positive I did it right and I'm not positive that it didn't get damaged when I took it out and put it back in.

There is an old thread that identified this fapper as being very important for the engine's cooling process. So, all that to say, before I pay $149 for a new flapper to test it, I thought I'd ask you all!

[TheCabinetmaker]

Are you talking about the flapper under the car that goes from the heat exchanger to the cabin, that provides heat?

[m170seeker]

Yes.

[Jeffs9146]

There is an old thread that identified this fapper as being very important for the engine's cooling process.

The "flapper" that affects cooling is the one inside the tin above the oil cooler! There is a wire that passes to the under side and a bellow that will open/close the flapper when the car is hot/cold!

[Katmanken]

Okay; I don't have a link to the Cooler Air kit but it is the dual condensor unit that AA sells. I don't think the AC system drag is heating it up. I can try the test (running it without the new air on) and report back on that one. Some of the sheet metal had to be cut out for the compressor but this kit is identical to the dealer installed kit so I don't think it is all that. the draft under the car changes due to a few cuts in the body and the ac hoses coming through the racket pinion steering cover. Also, not nearly as much space is left between the engine and the firewall with the condensor and the electric fan mounted there.

I'm hoping it is as simple as the heater flap being stuck or something. I removed it and reinstalled it (intending to put it back just like it was). I'm not positive I did it right and I'm not positive that it didn't get damaged when I took it out and put it back in.

There is an old thread that identified this fapper as being very important for the engine's cooling process. So, all that to say, before I pay $149 for a new flapper to test it, I thought I'd ask you all!

If I understand your dual condensor setup, you have one condensor mounted under the spare tire and one mounted in the engine compartment with a fan. Since each condensor vents heat, I would venture a guess that you are now dumping extra heat into the engine compartment from the engine compartment firewall condensor, and that extra hot air is now being used as cooling air to cool your engine.

Factory kit only had a front condensor.

Yep, that plus the cuts in the engine compartment sheetmetal will heat things up.

[m170seeker]

Very good points. I think I now understand how I was confused on the heater flapper(s).

I think I'll first drive it some without the ac on. Lets see what the extra drag is doing if anything. Then its seal up some of the tin cut outs and close up the rack and pinion steering cover opening.

[Dave_Darling]

.... not nearly as much space is left between the engine and the firewall with the condensor and the electric fan mounted there.

That sounds like at least part of the problem. You're heating up the engine bay air right in front of the cooling fan intake. I don't know how much more heat that puts out, but less space for air to get into the fan and hot air dumped right into the fan together are not a very good mix.

Clay has a big condensor on the engine lid of his wife's car, I believe. That should also heat the engine bay air, but possibly not by as much, in part because it's using less-hot air to start with and in part because that air has more of a chance to mix with any less-hot air that comes in through the rest of the engine lid. He does not report any cooling problems, at least not that I have heard of. Hopefully he will chime in here shortly.

I have never been a fan of the way the dealer-installed setup chopped up the engine tin. It seems like a recipe for recirculating hot air back through the cooling system. But other mounting options for the compressor seem pretty limited, so...


Finally, double- and triple-check that you have the cooling flaps inside of the engine tin, and that the flaps get into the "maximum cooling" position. Yes, those flaps are very different from the "flapper boxes" that are attached to the heat exchangers.

--DD

[Joe Owensby]

I am just curious. Did you have to cut the sheet metal that divides the top and bottom sections of the engine. I think AA had said they have a compressor mount that does not require this. I was thinking of getting one. I have one of the older style compressor mounts that sits directly in the middle of the tin that separates the top and bottom of the engine. It is pretty hard to get a real good seal to keep the hot air under the tin, but it can be done with a little sheet metal and rubber. I plan to look into the alternative compressor mount the next time I have to remove the engine.

I have an AC system on my 2.0. It adds a little increase in engine temps if it is about 98 or higher outside, and I am running over about 70 mph or so. I have an external oil cooler mounted under the trunk, and this takes care of any temperature issues that could arise. I really like riding around in a cool car.

The previous recommendations should help you trace down the problem to either incorrect cooling, or just added heat load.

JoeO

[m170seeker]

Thanks Dave and others. I'll keep at it.

Joe, my compressor requires a hole to be cut in the engince tin. In my case, the hole was already there as the PO had A/C from a dealer back in the day. The A/C equipment had been removed in the last refurb of the car.

[ClayPerrine]

We run a 911SC condenser fan on the inside of the engine lid on Betty's 914. It has two 10" fans on it, and we don't have any issues with engine cooling. And yes, we live near Fort Worth, and the car is driven daily.

The only time we had an issue was recently when we were pulling across the desert and losing oil at the same time. The oil temps climbed, but we turned off the AC and ran the fans on the lid with a separate power feed. It cooled the oil down enough for us to make SLC without an issue. The problem was low oil, not a lack of cooling.

Make sure all of the flapper pieces are there, and it should be fine.

[m170seeker]

Thanks Clay. That is encouraging.

[TheCabinetmaker]

I'll be picking your brain in the future Clay.

[m170seeker]

Update. Here is where we are now. Oil cooler installed but without the aux. electric fan to help it along. Fan is going in next week. Oil temperature per VDO gauge still shows that it rises to the bottom of the Red zone, but it does take longer with the oil cooler installed. Temperature of the oil pan is only 125 degrees.

I would like to test the oil temperature. Seems like another thread I saw references a dip stick or some other way to check the gauge.

Any suggestions?