AC issue

Have a question on the ac system on the Miata. Have a 90 with r12. Took it in and the pressure is good and has the correct amount of freon. But after 20-30 minutes of driving it stops working and starts to blow hot air, but then will come back on after a few minutes. Also, sometimes the rpms goes up to over 1500 to 2000 while at idle, stopped at a red light and such. Any ideas? Finding it hard to take it to a place that I trust and want to be able to go in and at least have some idea what might be wrong. Thanks.

Reply to
Mac
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I've no idea, I have the same AC problem but not the idle speed problem on my Jeep. Could possibly be known problem on the '93 Grand Cherokee, the computer fails to send a signal to turn off the compressor when it should and the unit ices up. I doubt there's anything similar on the Miata but who knows?

I also had a similar problem on the Miata two years ago, AC was cooling just fine and then started blowing hot, like the compressor was turned off. Next time I drove, same thing, no AC.

I suspected low freon causing the pressure switch to stop the compressor. I took it in and they said it wasn't leaking but added a can of dye.

A few days later, it stopped again but when I stopped the car it worked when I started it again and...... it's never failed since! Go figure. BTW, the dye showed no leaks.

I really doubt any of the above will help you any, sorry. Isn't there anyone you know that can recommend a shop? That's probably the best way to find a good one....

Reply to
XS11E

I've dealt with this issue on several cars. Each time it's been the same thing; the drain on the reservoir that the ac dumps the humidity into, clogs up and the reservoir gets full. AC quits working. Often times (but not always) combined with soaking the carpets in the floorboards from 'sloshing'.

Try this; car up on jack stands, running, ac on, (assuming it's not working), try running a wire up thru the drain hose from under the car. You know, the one that normally drips when the ac is running. Often times you'll be able to nudge some debris out of the way and the water will come rushing out (smelling like you-know-what! If this works, at least you've identified the problem. I haven't removed this and cleaned it out on a miata. Some cars it's easy, others, it's a royal pain. Alternative; try to suck the debris out with a shop vac and some creative hose adapters ;-)

Keep us posted, Chris

99BBB
Reply to
Chris D'Agnolo

Just for my general knowledge: where is this drain situated? I guess it runs from the evaporator to ???

Jeroen MX-5 Club Netherlands

| >> Have a question on the ac system on the Miata. Have a 90 with | >> r12. Took it in and the pressure is good and has the correct | >> amount of freon. But after 20-30 minutes of driving it stops | >> working and starts to blow hot air, but then will come back on | >> after a few minutes. Also, sometimes the rpms goes up to over 1500 | >> to 2000 while at idle, stopped at a red light and such. Any | >> ideas? Finding it hard to take it to a place that I trust and | >> want to be able to go in and at least have some idea what might be | >> wrong. | >

| > I've no idea, I have the same AC problem but not the idle speed problem | > on my Jeep. Could possibly be known problem on the '93 Grand Cherokee, | > the computer fails to send a signal to turn off the compressor when it | > should and the unit ices up. I doubt there's anything similar on the | > Miata but who knows? | >

| > I also had a similar problem on the Miata two years ago, AC was cooling | > just fine and then started blowing hot, like the compressor was turned | > off. Next time I drove, same thing, no AC. | >

| > I suspected low freon causing the pressure switch to stop the | > compressor. I took it in and they said it wasn't leaking but added a | > can of dye. | >

| > A few days later, it stopped again but when I stopped the car it worked | > when I started it again and...... it's never failed since! Go figure. | > BTW, the dye showed no leaks. | >

| > I really doubt any of the above will help you any, sorry. Isn't there | > anyone you know that can recommend a shop? That's probably the best | > way to find a good one.... | >

| >

| >

| > -- | > XS11E, Killing all posts from Google Groups | > The Usenet Improvement Project:

formatting link
| |

Reply to
Jeroen Feelders

Checked the drain and is it clear. Even took the hose off and checked it. Hose is located under the passenger side dash. will see it coming out of the evaporator. Ran the car for 15-20 minutes and the ac stayed on the whole time. Should it cycle on/off and if so how many times is normal or does it stay on all the time??? Does not seem like it is cycling right.

Reply to
Mac

I guess you still don't have many AC in the Netherlands. There is a short rubber hose that runs from behind the glove compartment to the transmission tunnel, passenger side of course. People with NA cars with AC get used to finding water on the floor at the passenger side and taking out the hose to unclog the exit of the evaporator enclosure behind the glove compartment by poking with a screwdriver.

Leon

Reply to
Leon van Dommelen

I'm getting this right now except that I usually find the water on my dog, who likes to curl up down there. I still get a little water out the hose underneath, but apparently not all of it. A left turn seems to set off a grand slosh that dumps a glassful or so all at once.

Are you saying the blockage is usually up in the under-dash unit rather than in the hose? I was going to blow air up from underneath but it sounds like taking the pipe off under the dash might be more useful.

miker

Reply to
miker

On my last Miata, I removed the tube and poked a straightened coat hanger wire into the box itself where I could feel it dislodging the debris and then a lot of dirty water would come out, with some of it even landing in the bucket I had in place.

I had to do this maybe 3 times over about 5 or 6 years. I could have removed the box and cleared the debris, but that it a fairly involved job.

BTW, the drain tube itself was never blocked in my experience, it was always the debris in the plastic box where the tube attaches, with this car and on at least 3 other NA Miatas that I have unblocked.

Pat

Reply to
pws

Going on 11 years for me. Haven't had a problem. Curious.

Reply to
Frank Berger

Ok, that was dead easy. Pull the tube off (no clamp or anything), poke a) stubby screwdriver; b) section of coathanger; c) hex key up there... as you say, I could feel almost a little crust I broke thru and water started draining. I caught most of it with a towel before realizing I coulda just put the dem tube back on.

miker

Reply to
miker

"Mac" wrote

I am not an A/C expert, but think there is a thermostat involved that shuts off the A/C when the temperature hits a certain point. If this thermostat is broken, the A/C continues to work until the coils freeze up. Then it begins blowing hot air. Once the coils unfreeze it works just fine. Until......

-- Ken Lyons '97 Brilliant Black/'90 Classic Red, both with working A/C Inside the Beltway [Remove the first two digits to reply]

Reply to
Ken Lyons

I assume you do not park under trees in Florida.

Leon

Reply to
Leon van Dommelen

Seemed like it wored better today. I did poke up in the drain hole but not if lossen anything or not. Will continue to check it more. Thanks for all the info. If have any other problems will check the thermostat.

Reply to
Mac

I'm thinking the bits of leaves get in thru the cowl at the base of the windshield. There's screen type of protection but with leaves drying and crunching up into small bits well, you know. They seem to make their way from there. I doubt 'garaged' miatas will ever have a problem.

Chris

99BBB
Reply to
Chris D'Agnolo

Well, I actually own a 91 Miata with AC and haven't noticed the drain before. Can't find it in the Workshop Manual too. Allthough I haven't got any problems with my AC I'll crawl underneath the glove compartment soon and have a look...

Jeroen

"Leon van Dommelen" schreef in bericht news: snipped-for-privacy@4ax.com... | "Jeroen Feelders" wrote: | | >Just for my general knowledge: where is this drain situated? I guess it runs | >from the evaporator to ??? | | I guess you still don't have many AC in the Netherlands. There is a short | rubber hose that runs from behind the glove compartment to the transmission | tunnel, passenger side of course. People with NA cars with AC get used to | finding water on the floor at the passenger side and taking out the hose to | unclog the exit of the evaporator enclosure behind the glove compartment | by poking with a screwdriver. | | Leon | | >Jeroen | >MX-5 Club Netherlands | >

| >| >> Have a question on the ac system on the Miata. Have a 90 with | >| >> r12. Took it in and the pressure is good and has the correct | >| >> amount of freon. But after 20-30 minutes of driving it stops | >| >> working and starts to blow hot air, but then will come back on | >| >> after a few minutes. Also, sometimes the rpms goes up to over 1500 | >| >> to 2000 while at idle, stopped at a red light and such. Any | >| >> ideas? Finding it hard to take it to a place that I trust and | >| >> want to be able to go in and at least have some idea what might be | >| >> wrong. | >| >

| >| > I've no idea, I have the same AC problem but not the idle speed problem | >| > on my Jeep. Could possibly be known problem on the '93 Grand Cherokee, | >| > the computer fails to send a signal to turn off the compressor when it | >| > should and the unit ices up. I doubt there's anything similar on the | >| > Miata but who knows? | >| >

| >| > I also had a similar problem on the Miata two years ago, AC was cooling | >| > just fine and then started blowing hot, like the compressor was turned | >| > off. Next time I drove, same thing, no AC. | >| >

| >| > I suspected low freon causing the pressure switch to stop the | >| > compressor. I took it in and they said it wasn't leaking but added a | >| > can of dye. | >| >

| >| > A few days later, it stopped again but when I stopped the car it worked | >| > when I started it again and...... it's never failed since! Go figure. | >| > BTW, the dye showed no leaks. | >| >

| >| > I really doubt any of the above will help you any, sorry. Isn't there | >| > anyone you know that can recommend a shop? That's probably the best | >| > way to find a good one.... | >| >

| >| >

| >| >

| >| > -- | >| > XS11E, Killing all posts from Google Groups | >| > The Usenet Improvement Project:

formatting link
| >| | >| | >

| -- | Leon van Dommelen :) Bess, the Miata :) Bozo, the Miata :) | snipped-for-privacy@dommelen.net

formatting link
| The only thing better than a white Miata is two white Miatas

Reply to
Jeroen Feelders

Excellent, I never thought to quickly put the tube back on, that is far too sensible.

I really wish that I had this problem to deal with right now.

As nice as it is not to have to worry about replacing an AC compressor, freon, etc., that cool air is kind of nice as well.

Pat

Reply to
pws

Seemed to work fine today driving home in near 90 temp. And have the nice puddle of water under the car when stopped. maybe it was clogged some. Will keep checking and clean it out more this weekend. thanks for all the help and discussion on this matter.

Reply to
Mac

Actually, Pat, I never had that problem with Belle in the 12 years I owned her. Don't know about the previous owner, but Belle was 17 when she died and I never had to unclog that line. She had nice cold AC as well.

Iva & ?

2004 Classic Red No more winkin' Miata
Reply to
Iva

My '92 has 145,000 miles and has no clog in the tube but living in the delightfuly pleasant summertime temperatures of Phoenix I seldom need the refrigeration....

Reply to
XS11E

Hmmm, I wonder why the ones I have worked on and the one that I used to own have it happen so regularly.

You must be casting the proper spells. :-)

It has never been a big problem, but definitely something that I have expected to deal with on any A/C equipped NA that I own. Not sure about the NB's and NC's.

You do keep your car a LOT cleaner than mine, that may have something to do with it.

Pat - waiting out the rain, again.

Reply to
pws

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