A/C Upgrade Project starts tomorrow!

[Mitch Leland]

Originally Posted by PSJoyce

Well, sometimes it’s the simple things.

Checking the vent temperature -- while the front trunk lid was open -- to make sure I hadn’t ruined something new while re-sealing the evaporator box to replace all the foam that had gone to dust, I noticed I could see daylight through the center dash A/C vent. Somewhere along the way in the last 24 years, the duct to the center vent had slipped off the vent. Reaching around from the front, but mostly reaching in through the clock hole, I was able push the vent back into place. I had always wondered why it didn’t seem like a lot of air was coming through the vent – much better now.

Paul

Paul gave me a good heads up... My A/C is barely cold, but beyond that it doesn't blow very hard. I want to be sure that the dash grill is lined up and the return air opening at the evaporator is clear.

Also I read on the PCA Tech site that a guy sealed off his passenger side foot well vent which increased the air flow from the dash grill. It might be worth trying as it doesn't involve anything permanent.

If I don't get any improvement in the A/C performance after that I'll consider some of the up grades.

[JeremyD]

Just wanted to add to this thread - I was coming back from Sebring DE and just happened to have my hand held thermometer in a carry all next to me so I thought I would shoot a vent temp - this is after a hour and 45 minutes in the car. List of changes:

All from Rennaire:

Desert duty front condensor
Serpentine evaporator
I lined the evaporator box with stick on foil back insulation
Barrier Hoses
Sanden 507 Compressor
new stock Receiver/Dryer
r134a

I'm pleased the way it turned out.

[scottb]

Originally Posted by JeremyD

Holy ice cubes, Batman!!

[Barrpete]

Shouldn't you be wearing gloves?

[deshetlr]

Jeremy why did you choose to go with the stock receiver/dryer over the Pro-Cooler? Looks like you are getting great performance without the extra complexity.

[JeremyD]

Cause I have 16 x 8 (951) wheels on my car 225/50/16's and I have heard some people having fitment issues with the pro cooler.

I figured that a new receiver dryer was 1/4 of the cost - and I could add one later if I needed to.

It was a gamble and a compromise - but I'm ok with that. BTW it was 92 on the bank temp sign down the street where I took this picture and pretty darn humid.

BTW that is a "F" not a "C"

[kuehl]

Jeremy,
Is your ac's thermostat system working properly?

[Mitch Leland]

Jeremy,

Wow, that's unbelievable, and without adding an extra condenser... I wonder why these vent numbers are all over the board?

I'm assuming the barrier hoses have nothing to do with the temp, but only with the bleeding off of the freon charge. So that leaves the front condenser and evaporator as real upgrades to reducing the temps on your car.

Do you additionally contribute the better cooling to the insulation of the evaporator box? If you hold your hand in front of the vent grill with the fan on high setting how far does the cold air throw from the face of the grill? My car is about 10"-12"...

[PSJoyce]

I compared an infrared thermometer, and a standard digital probe thermometer on my A/C vents the other day. The digital probe thermometer showed 40°, and the infrared varied from 14° all the way down to 0°. I shot the back of the probe thermometer with the infrared, and that was also 40°. I’m not sure of any of the physics, but the probe thermometer seems a better choice for measuring vent temps.

My other standard of comparison was my bare hand, and that got pretty chilly.

Paul

[JeremyD]

Originally Posted by kuehl

Jeremy,
Is your ac's thermostat system working properly?

Good point Kuehl - My thermostat switch is now on on off switch that I have to cycle - so yes, technically a thermostat switch would have cycled the compressor off before getting that low - I had a problem with the switch - but will replace it with a new stock one now that I know the system is working optimally.

As far as the thermometer is concerned - no I have not had it calibrated - yes it could have been off - Just one man's experience. I'm not trying to set a record of anything (BTW the black plastic surrounding the vent was 39 degrees)

[JeremyD]

My car ran at Sebring for a DE - was out in the sun all day - top up, windows open. at 4:00 I packed the car back up - put the windows up (I have a convertible) - Dark blue interior.

By the time I got to the gas station in down town sebring - I was feeling comfortable. less than 20 minutes and I cut the fan switch from full to 3/4 .

So yes, it seems the desert duty front condensor, coupled with a new compressor and a evaportor can have measurable impact on your stock AC system. Can it get colder? Sure. It would also be nice to have a little more fan volume - and less noisy - but is my car much more civilized in the summer? you bet.

[kuehl]

Infrared or non-contact temperature measuring is not tricky as long as you know what you are measuring and the limitations of the tool. If the tool has distance-to-spot ratio or D:S of say 24:1 that would mean when you are 24 inches away you may be measuring 1" diameter. The infrared tool can not measure the air temperature but it can measure the temperatures of the surfaces, and there are some surfaces and materials which can be provoking or testy in terms of the blackbody radiation emitted from the object: the angle in which you hold the tool in respect to the surface you are measuring is important especially for when the object has an emissivity of less than .9; the emissivity of the object, such as flat black vs. shiny reflective black can come into play with accuracy as well.

I prefer to use something with a thermocouple, and we try to use the same make and model unit with NIST (National Institute of Standards and Technology) traceability to insure what we are seeing is realistic.

I won't say whether you actually were getting 18F or not as "anything" is possible; I've driven my evaporator core below 9F with R134a playing with various charge rates and combinations of components. But what is more important is how well the system overall performs in removing the heat from the vehicle consistently and without crashing the compressor. So, safe high side pressures are what you want to focus on now.

You know that once you near 32F in the evaporator box on a humid day with the circuit you have you'll just have to turn the system off and let the ice thaw; so its time to fix the thermostat for sure.

The bottom line is that you felt comfortable after making some mod's and doing a proper evacuation and charge in you new ride, Cab's can be challenging to keep cool.

I might have something for you in terms of more CFM in the next month or two, we are still "testing" as they say.

Griff

[Mitch Leland]

After reading some previous threads I decided to look at the manifold connection at the back of the dash vent grill. As was suggested by an earlier posting that you can remove the clock for access which I did. The manifold was 1" away from the dash grill housing. I removed the fresh air blower, the plastic "Y" and related hoses. Once I had the A/C vent hose off of the manifold I was able to reach in through the clock hole and re-set the manifold housing back on to the dash grill vent. In fact I don't think you can get at the manifold housing from the trunk no matter how much you remove. So I probably removed things I didn't really have to.

The one thing that I think might have been a problem is that there is a metal tang sticking out of the firewall of the trunk that is directly under the A/C vent hose. When I re-installed the A/C supply hose I put the hose clamp over the metal tang so now the hose is anchored to the firewall which hopefully will keep the vent grill manifold housing in place.

I'm now getting a lot more air, but still not cold enough for hot Texas summer days. If Griff comes up with a higher CFM motor I'll be the first in line. Hopefully you'll be able to run it slower and get the same CFM we're getting now, but it will be quieter, at least you'll have choice of more air or run silent...

The corrugated hoses sure don't add up to a very efficient way of delivering the air. I bet if you could find a metric SCAT hose it would allow better air flow. Any thoughts out there on this.? It appears that you can improve on our A/C, but it takes a lot of small improvements to make it really work... and money...

[mtbguy]

I finished removing my old system this weekend after the weather here is getting hot and I am finally finding some free time. I was REALLY glad I pressure washed the underside of car recently because this was a dirty job.

My only casualty was I forgot about the capillary tube with temp sensor inside of it when removing evap box from car, and bent it up a bit. I can't seem to find a replacement one online and wonder if I just carefully re-install it would work okay. I don't think it was punctured/ruptured- just bent. Is this a universal part that can be bought at local A/C supply and spliced into system?

Now its time to braze on fittings for my SLHE (suction line heat exchanger) -Jim Sims subcooler.

[Barrpete]

I just bought one from Pelican for $50.

P/N 911-613-121-01-M145

It's on the electrical switches page not the ventilation/AC page.

[mtbguy]

Thanks Barrpete- that explains why I couldn't find it. Did you bend yours up also, or do they die of old age?

[Barrpete]

Originally Posted by mtbguy

Thanks Barrpete- that explains why I couldn't find it. Did you bend yours up also, or do they die of old age?

Apparently they die of old age. My AC was working fine & then suddenly no cold. Fans still blowing fine but compressor wouldn't kick in. Measured the voltage at the compressor & only got 7 V. Bypassed the switch & voila 12V again.

[mthomas58]

Originally Posted by mtbguy

I finished removing my old system this weekend after the weather here is getting hot and I am finally finding some free time. I was REALLY glad I pressure washed the underside of car recently because this was a dirty job.

My only casualty was I forgot about the capillary tube with temp sensor inside of it when removing evap box from car, and bent it up a bit. I can't seem to find a replacement one online and wonder if I just carefully re-install it would work okay. I don't think it was punctured/ruptured- just bent. Is this a universal part that can be bought at local A/C supply and spliced into system?

Now its time to braze on fittings for my SLHE (suction line heat exchanger) -Jim Sims subcooler.

How about posting some pics of your SLHE? BTW, just sent a PM regarding your capillary tube with some recommendations.

[mthomas58]

Commute home today............93 degrees........... 34 degree vent temps! Charlie, you're the man! Couldn't be more pleased with capability of the new system.

This was at the 5 o'clock temp dial setting and med fan speed.

[GH85Carrera]

Originally Posted by mthomas58

Commute home today............93 degrees........... 34 degree vent temps! Charlie, you're the man! Couldn't be more pleased with capability of the new system.

It was 94 here today. I drove my toy to work since it was Friday I had to turn the A/C down to medium fan speed on my trip home. It is only a 12 mile commute but I was getting cold.