- 04/18/2014
- 2 Min Read
- By: Alex Fiehl
My A/C Doesn't Work: Why '93-'04 Volvos Don't Blow Cold Anymore
It's about that time of year again...
Summer is coming and your Volvo 850's A/C still needs to be "topped up" every month. Don't be the guy in the Autozone parking lot recharging with a trigger can of R134a every week. Fix it right and fix it for good. The environment will thank you!
This guide covers all Volvo 850, S70, 98-00 V70 and XC, and 98-04 C70 models.
That being said, there are two primary reasons for a faulty A/C system in a 93-04 P80 chassis Volvo:
- Leaking evaporator core
- Improper compressor clutch gap
This will provide a cursory look at these issues and can get you started on the right track to properly repairing your A/C system without having to waste money on refrigerant every two weeks.
Introduction
I'd like to preface this post by saying it is NEVER okay for ANY A/C system to leak. If a mechanic or salesman tells you that it's normal for a car to need refrigerant added every once in a while, there is a leak. A/C systems are completely sealed and designed to hold their charge indefinitely. It is only when components begin to fail and seals begin to perish that the refrigerant finds its way out.
Leaking Evaporator Core
Volvo 850/S70/V70/C70 models are notorious for evaporators that rot out due to debris in the HVAC system. The best thing you can do to combat
this rot is to ensure your car has a cabin air filter installed. Some 850 models lacked a cabin air filter entirely, which can be retrofitted after the fact. Eliminating leaves, sticks, and airborne particulates from reaching the evaporator is your best shot at keeping the system from leaking down the road. This debris traps moisture on the evaporator core and allows it to stagnate on the fins, whereas this moisture would normally drain off of a clean core.
How will you know it's bad? If you find you're in a cycle of adding refrigerant to get the compressor to kick on, there's probably a leak. If there are no externally visible dye leaks from previous top-ups with "All In One" refrigerant (R134a+PAG oil+UV dye), then you've probably got a bad 'evap. If you've got a flexible camera, you can pop out the blower motor resistor and take a peek at your evaporator without removing the dash.
Remove the blower resistor to see the evaporator
Granted, replacing an evaporator is not an easy task. It involves complete dashboard removal to get to, and is at least a 2-day job for the uninitiated. But if you've got the tools and the time, it's a very rewarding experience that will save a ton of money over having a shop do it.
Compressor Clutch Gap
When the clutch on an A/C compressor engages, it uses an electromagnet to draw the clutch disc on to the compressor's serpentine freewheel pulley. The clutch disc is connected to the compressor's input shaft. When the clutch is engaged, the rotation from the serpentine system can be transferred into the clutch disc, causing engagement of the compressor pump.
If the gap between the clutch disc and serpentine pulley is too large, the electromagnet will not be able to draw the two plates together. This is a very common "No A/C" complaint, and can be easily remedied in 30 minutes with some home-brew shims.
The three red arrows indicate where to slide in your shims
A very common and successful fix among Volvo owners is the "Bread Clip Fix," where plastic bread tags are used to shim out the compressor clutch. If bread clips are too thick, a variety of materials with different thicknesses can be used here, as long as it brings the compressor clutch gap a bit closer. I coat the shims in contact adhesive before sliding them in to make sure they don't fly out during periods of high RPM. If you're having trouble getting the shims in, the clutch plate can be gently pried towards the serpentine pulley in order to allow a little more room for the shims. Be sure that a gap still remains between the pulley and clutch after performing this repair or else the compressor will never disengage.
A proper clutch gap should be between 0.3mm and 0.5mm. I use a spark plug gap feeler gauges to measure it. The compressor's clutch can also be removed and re-shimmed on it's hub to avoid using bread clips, but this method has been so successful I thought to share it as a viable alternative that saves hours of labor and compressor removal. Some shops even recommend to replace the whole compressor when the clutch gap is too wide!
Wrap-Up
If you're lucky, reshimming the A/C clutch will have you on your way to a cool summer. If not, you'll most likely have to crack the system and service the evaporator if there are no other external leaks present in the system. It's uncommon (but not unheard of) for the original evaporators to still be serviceable at this age, so keep it in mind.
When replacing an evaporator, be sure to buy two Genuine Volvo seals, a new orifice tube, and a new receiver/dryer for the system. Pull a vacuum on your newly serviced and sealed system for at least an hour in a warm garage, and recharge with 1.63lbs (26.08oz) of refrigerant when you can confirm no drop in vacuum after removing the pump. (Exactly 2 cans or 24oz works perfectly if you don't have the equipment to perform an exact charge) Don't skimp on the vacuum service - keeping it under a strong vac for an hour or two will boil off any moisture in the system and ensure it provides you years of rot-free service.
About the Author: Alex Fiehl
Alex is FCP's Blog Editor and an IT technician from Endwell, NY. He has over 8 years of experience working on a wide array of import makes, but lately is partial to Volvo . For some reason he just purchased a Volkswagen, and is excited to see what breaks first.
