1991 Olds 98 Regency Elite A/C problem

[Don Hanson]

I'm restoring my 1991 Olds 98 Regency Elite a little bit at a time. The car had 103,000 original miles on it when purchased 4 years ago. I rebuilt the entire air conditioning system. New parts that have been installed- compressor, compressor switches and relays, accumulator, switch on accumulator, condenser, 4 orifice filters, all new O-rings, and new cooling fans. I cleaned the outside of the evaporator coil in the dash using a a/c coil spray cleaner and rinsed it thoroughly. The entire system was flushed with 90% Isopropyl alcohol by a reputable professional A/C mechanic. Then the system was charged with oil and R134a refrigerant by the same a/c mechanic. The system cools very well as long as the car is moving down the road. When I stop and let the car idle, like at a traffic light, the air coming out of the vents starts warming up. Also, while stopped with the engine idling and a/c on, the temperature of the engine begins to climb. If I turn off the a/c, the engine temperature begins to drop.

 

Also, in the Summer of 2022, I did a thorough flush of the cooling system using the proper chemicals. I flushed the cooling system until nothing but clear water came out. I replaced all radiator hoses and heater hoses. I filled the system with new coolant and distilled water. A new thermostat was installed at the time.

 

Does anyone have any ideas as to why all this is happening?

 

I do have a Bosch OBD 1300 scanner I can hook up to the car. It's a basic model that will give real time readings while the car is running. It was $280 so it's not a high-end tool.

Edited May 15 by Don Hanson
More information came to mind (see edit history)

[ted sweet]

cooling fans not working?

[EmTee]

Check that the cooling fans are working properly.  I don't know the particulars for this car, but sometimes there's a second fan that comes on with the A/C, or the fans will speed-up when A/C is on.  It sounds like there isn't enough air moving through the condenser/radiator.  Ensure the fins are clean and there's no blockage (e.g., leaves, or other debris).

[Ronnie]

1 hour ago, Don Hanson said:

When I stop and let the car idle, like at a traffic light, the air coming out of the vents starts warming up.

I agree, cooling fans are the first thing to check. Have you looked to see if the compressor clutch is still engaged when the air coming out of the vents starts to warm up?

 

[Ben Bruce aka First Born]

Does the engine idle faster when the A/C is on than it does when A/C is off?  It should.  Perhaps ask the reputable professional A/C mechanic.

 

  Flushing the cooling system WILL NOT always be good enough.  It may NEED rodding out.

 

  Ben

[pfloro]

It sounds like you had a knowledgeable and experienced auto A/C mechanic. Did he explain to you that one of the problems which effects some R12 -> R134a conversions is less idle & low speed cooling?

 

Here's why:  The condenser in your Olds (even though it's new) was designed for R12.  Simply put, R134a needs more condenser surface area to transfer the heat from the high pressure gasous refrigerant to the air.  Unless that happens, some of the R134 doesn't condense back to a liquid and can't evaporate again (and absorb heat) in the cabin evaporator.  

 

Look at auto A/C condensers in post 1995 cars (which are R134a based).  They have a much denser configuration (more surface area).  The tubes are flat, there are many more rows, and there are many more fins between them.  Many of these designs use "parallel flow". Instead of the high pressure gas "surpentining" back & forth, it enters a vertical cylinder at one side. The refrigerant then flows across the flat tubes in parallel to a vertical cylinder at the other side.  This is all about getting maximum efficiency within the "small" condenser footprint. 

 

What can you do:

1)  The most practical solution is going back to using  R12. I don't know if NOS or recycled R12 is even available anymore.

2) This is probably not practical and prohibitively expensive.  Have a custom condenser built to fit your footprint, etc. which is designed for R134a.

 

IMO, Under no circumstances should you use any of the Drop in R12 replacement blends (with those kooky names).  They are at best, a cheap short term "fix" and can cause havoc over time.  

***

 

I'm not an A/C expert but have studied refrigeration for decades. There is alot of information about your exact problem on the net.  Much of it is written by engineers and auto A/C service people. I have spoken to my trusted HVAC man about this over the years and he agrees.  Did you ever wonder why the outside condensing units for multi-ton home systems (not mini-splits) became so big?  The newer residential HVAC systems use R410a which is somewhat similiar to R134a.  The condenser requires a larger surface area than was needed for the old R22 refrigerant.  For a residential system, going larger is not a big problem.  However, for an automobile... Oh Boy...

 

Paul

 

Edited May 16 by pfloro (see edit history)

[pfloro]

19 hours ago, Don Hanson said:

Also, while stopped with the engine idling and a/c on, the temperature of the engine begins to climb. If I turn off the a/c, the engine temperature begins to drop.

R134 is a less efficient refrigerant than R12. It operates at much greater pressures (especially the high side (condenser)) and greater temperatures.  This increased heat is being directly transfered into your engine cooling system.  Some cars tolerate R134a without a hiccup, others don't.  

 

Edited May 16 by pfloro (see edit history)

[pfloro]

13 hours ago, Ben Bruce aka First Born said:

 

  Flushing the cooling system WILL NOT always be good enough.  It may NEED rodding out.

Yes..., Ben Bruce is correct.  In your case, Given the car's age and mileage, it may be cheaper to replace the radiator.  I suspect that by 1991, GM may have started using aluminum cores with plastic tanks.  That configuration cools well and they are durable.  Replacement radiators should be available without a problem...

 

Paul

[61polara]

This car was built with a 134A sytem.  Are your cooling fans working?  What is the flow through the radiator.

 

[pfloro]

41 minutes ago, 61polara said:

This car was built with a 134A sytem.

Oops..., My error.  I wasn't aware that GM converted to R134a prior to around 1994...

 

I hope the OP responds so that we can help...

 

 

 

Paul

Edited May 17 by pfloro (see edit history)

[meteor]

When you are stopped at idle and have lower rpm's the suction pressure goes up

and so does the cooling temp. Try increasing your idle a little. Some cars increase

idle speed when the ac is on.

Roger

[61polara]

We really need to know what the AC system pressures are doing on both the high and low side to help you any further.  We are all just guessing until we know what the pressures are.  Also let us know how the pressures change from idle to 2500 rpm.

[Ben Bruce aka First Born]

1 hour ago, 61polara said:

We really need to know what the AC system pressures are doing on both the high and low side to help you any further.  We are all just guessing until we know what the pressures are.  Also let us know how the pressures change from idle to 2500 rpm.

 

  Don't count on it!  I fear OP lost his way.

 

  Ben 

[pfloro]

Don't waste anymore time with this OP.  He is a "OPW" (One Post Wonder).

 

I've had it with these people.  They are selfish takers. We're the words "Please" or "Thank You" used in his initial request?  

 

Yes..., I know that we all lead busy lives.  However, when one asks for help on this great forum, it is their responsibility to 1) follow the topic, 2) do homework, 3) answer questions from others who are trying to help.  It's no different than when selling something. 

 

As my mother would say:  "They can just SCHOTTA!   It's an Italian slang meaning bust. 

 

Paul

Edited May 18 by pfloro (see edit history)

[Don Hanson]

I'm posting here again to apologize to those who are offended that I didn't respond to those who asked questions in order to try and help me. The day after posting my problem here, I was attacked and severely injured by a dog that was running loose in my neighborhood. My right hand and left thigh were injured badly. I was diagnosed as having PTSD well over a decade ago, and the experience threw me into a deep depression with lots of anxiety, and I forgot all about this post. The experience pretty well caused me to shut down mentally and emotionally. I didn't think about this post again until a close friend, who I had told about posting here, told me that some of you were angry. I'm still not over the experience, but I remembered tonight that I needed to come back here and apologize, and also explain. I do apologize.

 

I'm happy to report that my friend spotted the problem. I replaced both cooling fans behind the radiator in September of 2023. I've since learned that the bigger fan on the driver's side is the radiator cooling fan. The smaller fan on the passenger side cools the condenser. While troubleshooting a couple of weeks ago, my friend noticed that the condenser cooling fan on the passenger side was turning the wrong direction. It was blowing air out of the engine bay through the front of the grill. I had noticed that when I reached a speed of 30 mph, the air coming out of the vents started getting colder. I'm thinking that the ram air coming through the grill overpowered the condenser cooling fan blowing air forward, and the condenser actually started getting cooled off. We left the condenser fan unplugged from power, and the A/C is cooling MUCH better.

 

Now the problem is that there is not a supplier that I can find that sells a condenser fan that rotates in the right direction. My plan is to get a fan at the local wrecking yard, replace the motor, and install it. I find it strange that all condenser cooling fans offered today all spin in the wrong direction. And no, there is not a way to reverse the fan blade. That idea cane up already.

 

Thank you to everyone who tried to help. I wish all of you well.

 

Don Hanson

[Larry Schramm]

10 minutes ago, Don Hanson said:

I'm posting here again to apologize to those who are offended that I didn't respond to those who asked questions in order to try and help me. The day after posting my problem here, I was attacked and severely injured by a dog that was running loose in my neighborhood. My right hand and left thigh were injured badly. I was diagnosed as having PTSD well over a decade ago, and the experience threw me into a deep depression with lots of anxiety, and I forgot all about this post. The experience pretty well caused me to shut down mentally and emotionally. I didn't think about this post again until a close friend, who I had told about posting here, told me that some of you were angry. I'm still not over the experience, but I remembered tonight that I needed to come back here and apologize, and also explain. I do apologize.

 

I'm happy to report that my friend spotted the problem. I replaced both cooling fans behind the radiator in September of 2023. I've since learned that the bigger fan on the driver's side is the radiator cooling fan. The smaller fan on the passenger side cools the condenser. While troubleshooting a couple of weeks ago, my friend noticed that the condenser cooling fan on the passenger side was turning the wrong direction. It was blowing air out of the engine bay through the front of the grill. I had noticed that when I reached a speed of 30 mph, the air coming out of the vents started getting colder. I'm thinking that the ram air coming through the grill overpowered the condenser cooling fan blowing air forward, and the condenser actually started getting cooled off. We left the condenser fan unplugged from power, and the A/C is cooling MUCH better.

 

Now the problem is that there is not a supplier that I can find that sells a condenser fan that rotates in the right direction. My plan is to get a fan at the local wrecking yard, replace the motor, and install it. I find it strange that all condenser cooling fans offered today all spin in the wrong direction. And no, there is not a way to reverse the fan blade. That idea cane up already.

 

Thank you to everyone who tried to help. I wish all of you well.

 

Don Hanson

 

Try swapping the wires of the fan motor in the connector and see what happens.  I will bet it will work correctly.  I have seen your problem before.

Edited July 7 by Larry Schramm (see edit history)

[pfloro]

1 hour ago, Larry Schramm said:

 

Try swapping the wires of the fan motor in the connector and see what happens.  I will bet it will work correctly.  I have seen your problem before.

I am so sorry to hear about your accident.  Please take time to heal.

 

Larry Schramm is correct.  I'm sure that the electric fan motors are Direct Current. Reversing the polarity will cause them to rotate in the opposite direction.   Think:  permanent magnet power window & seat motors.

 

At present, not only is the condenser fan "pushing" engine bay air through the condenser, it's also pushing the hot radiator air through it... Ouch...!

 

Paul

Edited July 7 by pfloro (see edit history)

[EmTee]

Check the connector plug at the fan motor; it should be polarized to prevent it from being inserted the wrong way.  Two possibilities: (1) someone was able to jam it in backwards at some point in the past which damaged the feature designed to prevent incorrect polarity or, (2) the original connector was replaced and wired backwards.

[Larry Schramm]

6 minutes ago, EmTee said:

 the original connector was replaced and wired backwards.

 

My guess

[Don Hanson]

I'll try reversing the wires and see what I get. Thanks for the suggestions everyone.

 

pfloro- I had considered that heat from the engine bay was being pushed out, but had NOT considered that radiator heat was being pushed through the condenser as well.

Edited July 8 by Don Hanson
Added additional thought (see edit history)