Mediocre A/C

[zyal8r]

Hi All... question on air conditioning... had my '95 out yesterday (5900 miles). I had added freon a year ago after it didn't blow any cold air, and got it to blow pretty cool most of the time, and cold sometimes when set at a decent temperature... about 72-74. Yesterday was very hot here in the Kansas City area (and the next several days), about 100*, but was dying to go for a ride as it'd been a while. I thought I'd make sure it was full (knowing the system was okay at best on a hot day), and it would not take anymore freon, the low side gauge would go in to the red, but the compressor was cycling on and off throughout this process, and the air didn't stay cold. I had the temperature down as low as it would go, and fan set on high. So the air throughout this ride was what I'd call mediocre... and I left the temp on 60 the whole way (about 20 miles).

I know that the ZR-1's A/C is different/smaller than the LT1/4, thus the windshield (and let me tell [show] you... if there is any ZR-1 windshield that is blocking rays... it's mine!!).

Just wondering how everyone else's experiences are on a 100* day - are you comfortable and is it blowing cold air the whole time? Do I have an issue? I haven't scanned for codes yet but I will when I have some time. Also, after one hard pull, my check engine and service ASR lights came on for a few minutes and I felt some stumbling.

I should mention that I had to put a new battery in it before this ride. It was down for a few weeks during a vacation, etc.

Anyway, pics of the windshield which by all means is REALLY good at blocking the sun! (Sorry I can't get it to rotate... tried from PC and from phone... turn your head!) :dontknow:

19771

Thanks for reading!
Mike

[HAWAIIZR-1]

Here you go from Marc Haibeck. Some have done this and on my bucket list too.

http://www.zr1specialist.com/HAT%20Web/articles/Improving%20AC%20Performance%20on%20the%20ZR-1.pdf

[zyal8r]

Thank you here as well, Sir! Appreciate it!

Mike

[HAWAIIZR-1]

You?re welcome Mike!! Best wishes. 🤙🏼




Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[rufcar]

I bought my 90, #2815 in April with the wrong compressor. I found the correct unit and I changed out the dryer. Then I had my local shop purge the system and install R12. R12 is colder than 134 and because it has larger molecules it does not leak as easy. Finally, my car came with only the blue clear top, which when in direct sun its next to impossible to cool. I found an original 90 red hardtop and installed it. Last item was the car came with tinted side windows. All combined on 100 deg days it is super cold in my 90 zr1.

[zyal8r]

I bought my 90, #2815 in April with the wrong compressor. I found the correct unit and I changed out the dryer. Then I had my local shop purge the system and install R12. R12 is colder than 134 and because it has larger molecules it does not leak as easy. Finally, my car came with only the blue clear top, which when in direct sun its next to impossible to cool. I found an original 90 red hardtop and installed it. Last item was the car came with tinted side windows. All combined on 100 deg days it is super cold in my 90 zr1.

Great points, thank you! Mine currently has the blue top on it (albeit with the factory paper/label inside), but my windows are not tinted. I am used to my '96 which does have tinted windows and solid top - that car will freeze me out. I will definitely remember this on the Z and change the tops out at some point. Now that it's getting cooler though, probably not an issue for a while.

Now just to get the *#@(*(!&!^&! windshield taken care of, whenever I can get one!

Mike

[1991 Corvette ZR-1]

I rebuilt my compressor, changed out the rubber hoses to the compressor, new accumulator, new condenser, new orifice tube filter, did the Marc Haibeck blower speed upgrade and recharged with R134a. I spent a lot of time pressure testing the system and slowly eliminating leaks. My AC works well enough.

It?s my understanding that the condensers used on the 90-93 cars were meant for R12 and therefore do not allow proper cooling to take place. As was mentioned, R134a will slowly leak out of the hoses not approved for it. Which, unfortunately, anything less than NOS hoses meant for a 94-95 probably will not work keeping refrigerant in.

The aluminum hard line on the passensger side with pressure switches is porous and may allow R134a to leak through. I pressure tested the hard line under water for 24 hours and it held pressure steady. Pulled a vacuum on it for 24 hour, same result. I have noticed there is a light coating of what appears to be compressor oil that has sweat through the hard line in some spots.

[WARP TEN]

...Anyway, pics of the windshield which by all means is REALLY good at blocking the sun! (Sorry I can't get it to rotate... tried from PC and from phone... turn your head!) :dontknow:

19771

Thanks for reading!
Mike

Hi Mike--I just posted this on another thread the other day. Tried to send it via PM but I can't see in my system that it got to you. So here it is. Hope it helps. --Bob



Originally Posted by phrogs View Post
I also have no idea why the photos twisted on me. I resized them and still twisted click on them and they are right side up.

Hey Phrogs--If you took them with an iPhone the default setting for it is landscape and if you post pix taken vertically on some websites they will be flipped 90 degrees. One solution for this (there may be others) is to load them onto a Windows computer and use the Paint program. Open each in Paint, select rotate, rotate first right, then rotate left, then save it. That will remove that default landscape setting and you can straighten them with any program and they will stay. You can also edit them on the iPhone, which allows you to flip them, but I don't know if that makes the change permanent. I know this sounds a bit cumbersome, but I have been doing it for a long time and normally just have a few pics to correct at a time and it is no problem for me., I also use the simple Windows program Microsoft Office (mine is a 2010 version) to crop, lighten and make other simple editing changes. Give it a try and see if it works. If it doesn't, well, the advice you get from me is worth what you pay for it!

[zyal8r]

Hi Mike--I just posted this on another thread the other day. Tried to send it via PM but I can't see in my system that it got to you. So here it is. Hope it helps. --Bob



Originally Posted by phrogs View Post
I also have no idea why the photos twisted on me. I resized them and still twisted click on them and they are right side up.

Hey Phrogs--If you took them with an iPhone the default setting for it is landscape and if you post pix taken vertically on some websites they will be flipped 90 degrees. One solution for this (there may be others) is to load them onto a Windows computer and use the Paint program. Open each in Paint, select rotate, rotate first right, then rotate left, then save it. That will remove that default landscape setting and you can straighten them with any program and they will stay. You can also edit them on the iPhone, which allows you to flip them, but I don't know if that makes the change permanent. I know this sounds a bit cumbersome, but I have been doing it for a long time and normally just have a few pics to correct at a time and it is no problem for me., I also use the simple Windows program Microsoft Office (mine is a 2010 version) to crop, lighten and make other simple editing changes. Give it a try and see if it works. If it doesn't, well, the advice you get from me is worth what you pay for it!

Hi Bob - thank you! I read this on phrogs' thread the other day and appreciate you pasting it here for me. I will definitely give it a try. I think I had gotten this to work on other pictures I've posted, but, this time was more stubborn. Will try again when I get a minute, thanks!

Mike

[Matt B]

My 91 has r134 in her A/C (combined with a special refrigerant oil and a slight adjustment to the - if I remember correctly - high pressure switch) and the system works amazingly well.
I always drive her with the blue bubble top on and up to about 95? the A/C works as it should. However 95 is as hot as it gets here so maybe it lacks performance beyond 95 - I wouldn't recognize it.

[Corvette95]

So, I did the Haibeck mod back in 2020, very nominal improvement but my A/C does keep up here in Alabama on a 100 degree day but takes a while to cool off after sitting in the sun with windows up and glass top on (which is rare that it's parked anywhere). I had the heater box out anyway and found the foam insulation ALL around the heater box to firewall disintegrated to nothing. I could feel the air coming from around the firewall. I took high temp butyl tape all around the box to firewall and the line exiting the accumulator. Made a decent (not a breakthrough) increase in airflow. I am using OEM windshield BTW. I have been wandering if another GM blower would be a direct fit that has a high Air Flow per Minute? Thinking of GM SUV's....has anyone tried to find a higher flow direct fit blower motor?

[Corvette95]

So, I did the Haibeck mod back in 2020, very nominal improvement but my A/C does keep up here in Alabama on a 100 degree day but takes a while to cool off after sitting in the sun with windows up and glass top on (which is rare that it's parked anywhere). I had the heater box out anyway and found the foam insulation ALL around the heater box to firewall disintegrated to nothing. I could feel the air coming from around the firewall. I took high temp butyl tape all around the box to firewall and the line exiting the accumulator. Made a decent (not a breakthrough) increase in airflow. I am using OEM windshield BTW. I have been wandering if another GM blower would be a direct fit that has a high Air Flow per Minute? Thinking of GM SUV's....has anyone tried to find a higher flow direct fit blower motor?

[Neat]

I didn't read the entire thread, apologies if I'm regurgitating something that's been said already:

I've noticed the AC on mine works great at first, but the blower motor slowly loses oomph over time. After an hour or so, I'd guess the AC output is 10% of what it was when I first started the car. If I turn off the car for awhile (stop and eat lunch / dinner) the AC returns to good performance, and then again degrades over the next hour or so.

I think my issue is the blower motor resistor warming over time, which (I think) is adding resistance over time, which is (I think) mimicking the driver commanding less air flow / blower speed. Eventually I'll rig a way to hotwire the blower motor to the "high" setting to check my theory.

If your issue is air output VS air temperature, the blower motor resistor might be worth considering.