LaserSVT is da MAN! .. but I gotta question. Did a search. :squint:

[Myco]

Thanks laser for the HVAC. Works perfectly and it solved the issue of my ac fan blowing all the time. Very happy about that. I'm guessing the last HVAC unit was from a gen 1.

Though that was only half the problem. One of the problems was the AC wasn't blowing hard out of the dash.

Since summer has started I've started using the AC at night and I've noticed that the car will definitely loose power when I turn on the AC. Though it doesn't loose power just once. It does a kinda stutter thing where the car will slow... then speed up again.. then slow. So maybe compressor is going bad?

I talked to my mechanic and he said that the low amount of air coming out of the vents could definitely be a compressor on it's last legs. ( it holds it's charge just fine. )

I've done a couple searches and I haven't seen anyone say slow blow from the vents could be traced to a bad compressor so I thought I'd ask you guys.

?

Thanks

 

[slowmkviii]

Are you having up and down air flow or up and down temp of the air flow

 

[Myco]

Are you having up and down air flow or up and down temp of the air flow

Flow. I have my heater by-passed but the temp does change with the control unit. The flow changes also but at it's max it is pretty weak.

 

[CobraStar_LS8]

change in temp is the a/c system...change in fan speed is the blower behind glove compartment or the eatc unit

 

[thaywood]

Honestly, I'm not well versed on HVAC systems, but I would assume that the "slow blow" if I'm understanding you correctly, would mean that your blower motor may be giving up the ghost. The compressor, as far as I know, has nothing to do with the volume or speed of the air coming out of the vents. That is controlled by the blower motor. If the air was not cool when the a/c is on, that may be attributed to the compressor wearing out, or lack of refrigerant in the system. My '97 LSC has the same issue with power when the a/c is turned on. I can definitely feel a decrease in power when the a/c is on. But it doesn't start and stop. The compressor runs constantly and I have very cold a/c. It just seems like the compressor is seriously dragging the engine down when it engages. The sensation is similar on my '96 Cobra. I can feel a decrease in power when the a/c engages on it too, just not as much as on the Mark. They both probably need new compressors

change in temp is the a/c system...change in fan speed is the blower behind glove compartment or the eatc unit

Haha! You beat me to it while I was typing

 

[Myco]

I've put in a new blower motor controller ( from junk yard ) this week. Just mentioning that as someone referred to that in a post.

I've also taken the fan motor out and watched it spin in my hand. Maybe it doesn't spin fast enough? I don't know as I don't have anything to reference it too. :dunno:

 

[LaserSVT]

No problem. I am not the man, only A man. :lol:


The air speed is because the blower motor is on its way out. The car stuttering when the AC comp kicks in could be one of three things.
Overcharged
Compressor is going out
IAC is sticking

 

[Myco]

IAC is new and the compressor was charged only once (about 3 months ago) since I bought the car. I could take it back to the shop and have him check it. He'd be glad too.

Edit: also, might hit up a junk-yard tomorrow and grab a blower motor as I know it's there.

 

[Raped Ape]

The air speed is because the blower motor is on its way out. The car stuttering when the AC comp kicks in could be one of three things.
Overcharged
Compressor is going out
IAC is sticking

Or it has a slow leak somewhere and the system is low on refrigerent. If the compressor is cycling rapidly, then that suggests that the system is on the low side. Even if a compressor was worn out, being worn would not create rapid cycling, but that of a low charge.

 

[LaserSVT]

Or it has a slow leak somewhere and the system is low on refrigerent. If the compressor is cycling rapidly, then that suggests that the system is on the low side. Even if a compressor was worn out, being worn would not create rapid cycling, but that of a low charge.

True but I didnt mean to imply a worn compressor would be turning on/off but that its bearings may be getting hung up as may the lobes on the compressor.
Also since he has stated before that the system was reciently recharged and its easy to overfill then that may be a problem.

On that same note if the system was not charged properly then there maybe air in the system or moisture both of which will cause comp issues.

 

[LSC HUNTER]

One of the things that most people do not do is vacume the system properly. On an automotive system it is less likely to cause a problem as there are no electrics in the system as an electricaly driven compressor. With the electricly driven compressor, when the system is not evacuated completely and there is some air in the sytem it will also contain moisture. When the moisture in the system mixes with the refrigerant it causes an acid to form and then all hell breaks loose breaking down the windings of the motor and causing a burn out. Bye Bye.

An auto system will just work like chit depending on the level of non condensables in the system. If there is that much of a load when the compressor clutch engages that it causes the motor to slow and rev then I would look at the compressor getting ready to pack it in. The other thing to consider is that since the auto system is small we really do need to weigh in the charge to get it running correctly. No matter what kind of system, pressure is temperature and temperature is presssure.

As stated before the compressor has no interconnection with air flow so if the air flow is weak then the blower is baked or the EATC is sending the air somewhere else or the evap coil is coated in crap restricting the air flow. I have seen carpets of dog fur on the evap face.

A few things to consider here.

 

[Myco]

One of the things that most people do not do is vacume the system properly. On an automotive system it is less likely to cause a problem as there are no electrics in the system as an electricaly driven compressor. With the electricly driven compressor, when the system is not evacuated completely and there is some air in the sytem it will also contain moisture. When the moisture in the system mixes with the refrigerant it causes an acid to form and then all hell breaks loose breaking down the windings of the motor and causing a burn out. Bye Bye.

An auto system will just work like chit depending on the level of non condensables in the system. If there is that much of a load when the compressor clutch engages that it causes the motor to slow and rev then I would look at the compressor getting ready to pack it in. The other thing to consider is that since the auto system is small we really do need to weigh in the charge to get it running correctly. No matter what kind of system, pressure is temperature and temperature is presssure.

As stated before the compressor has no interconnection with air flow so if the air flow is weak then the blower is baked or the EATC is sending the air somewhere else or the evap coil is coated in crap restricting the air flow. I have seen carpets of dog fur on the evap face.

A few things to consider here.

I have a new thread about this but here goes...

after 2 days of having the new HVAC in the motor is running continually again. The relay is 2 weeks old out of a junk yard car. Hvac is 2 days old. I bought a new motor from Gman last night to put in today.

When I pulled the dash I tried to find something in there that could be blocking but came up with nothing. Where is the evap coil?

 

[LSC HUNTER]

The evap coil is in the HVAC system behind the glove box. It is there along with the heater core in the black box that is an extreme biotch to get to.

I have never taken one out of a Mark and I would really think that the best way would be to do as Gman is doing, move the dash right out of the way. That is only my opinion and if someone has a better idea then I would do it that way.

Getting to the evap doesn't sound like that is your problem. If everything was working before and you don't travel with animals in the car then don't go looking for trouble. Sounds to me like it is a control problem so take your time and keep looking before you get off track. Start from the basics again step by step and move forward from there.

 

[GMAN]

I think we need to replace the WHOLE AC box. While the Pick a Part is half price this weekend. Now is the time to get it.